OPINION
MONTEMURO, Justice.Appellant, Shirley Cochran, appeals from an order and memorandum opinion of the Superior Court affirming an order of the Court of Common Pleas of Allegheny County granting Appellees’ motion for summary judgment based upon the statute of limitations.
The issue presented in this case 1 is whether the trial court properly held that Appellant’s claims were barred by the statute of limitations and not -within the “discovery rule” exception because of a failure to exercise due diligence in pursuing the cause of decedent’s illness.
*214The decedent, William Cochran, worked at Jones & Laughlin Steel from 1943 to 1944 and from 1949 to 1982 as a boilerhouse attendant, steelworker and bricklayer. On June 3, 1981, Mr. Cochran was admitted to the hospital for back pain. During this hospitalization, a right upper lobe resection was performed, resulting in a diagnosis of adenocarcinoma. At that time, the decedent had been smoking one-and-a-half packs of cigarettes daily since 1947. In response to the diagnosis of cancer, Mr. Cochran stopped smoking. There was no discussion at this time that the lung cancer was caused by work-related asbestos exposure.
On March 3, 1985, Mr. Cochran was again admitted to the hospital after several chest x-rays revealed the presence of a mass in the lower lobe of his left lung. A bronchoscopy and wedge resurrection were performed, and pathology reports confirmed the presence of a malignancy. The 1985 admission records make the first reference to Mr. Cochran’s exposure to asbestos.
Following this hospitalization, Mr. Cochran contacted an attorney who arranged for Dr. Howard E. Reidbord to review the tissue slides from both the 1981 and 1985 admissions. An August 7, 1985 report by Dr. Reidbord opined that both pulmonary carcinomas were related to asbestos exposure. This report revealed that slides prepared at the time of the 1981 resection contained asbestos bodies in the pathology material.
Appellant initiated the instant action by filing a complaint on September 27, 1985. The complaint alleged that Mr. Cochran was totally disabled from carcinoma of the lung and asbestosis as a result of his exposure to asbestos-containing products manufactured by the various defendants during the course of his employment. In December of 1985, Mr. Cochran died. The Appellees filed a motion for summary judgment contending that the decedent knew or should have known his lung cancer was asbestos related in June of 1981, more than two years prior to initiating his suit. Appellant maintained that the decedent never knew, or had reason to know that his lung cancer was asbestos related until the receipt of Dr. *215Reidbord’s report on August 7, 1985, and, therefore, the suit was filed well within the two year limitations period. The trial court granted the motion for summary judgment, a panel of the Superior Court reversed the trial court, and an en banc panel of the Superior Court reinstated the order of the trial court.
Appellant asserts that the en banc panel of the Superi- or Court incorrectly concluded that the Appellees were entitled to summary judgment as a matter of law. Instead, she argues that the issue of whether the decedent should have known he had an asbestos related cancer in 1981 was an issue for the jury. Our standard of review in this matter is well established. A trial court’s order granting summary judgment will not be reversed unless it is established that the court committed an error of law or clearly abused its discretion. Holmes v. Lankenau Hosp., 426 Pa.Super. 452, 457, 627 A.2d 763, 765 (1993), appeal denied, 538 Pa. 671, 649 A.2d 673 (1994); DeWeese v. Anchor Hocking Consumer and Indus. Products Group, 427 Pa.Super. 47, 50, 628 A.2d 421, 423 (1993). Thus, we must determine whether the trial court committed an abuse of discretion or an error of law in entering summary judgment in this case.
Where the issue involves a factual determination regarding what constitutes a reasonable time for the plaintiff to discover his injury and its cause, the issue is usually for the jury. Hayward v. Medical Center of Beaver County, 530 Pa. 320, 325, 608 A.2d 1040, 1043 (1992); Smith v. Bell Telephone, 397 Pa. 134, 142, 153 A.2d 477, 481 (1959). This is the general rule we set forth today. However, we also recognize the well established principle that where the facts are so clear that reasonable minds cannot differ, the commencement period may be determined as a matter of law. Hayward, 530 Pa. at 325, 608 A.2d at 1043 (quoting Sadtler v. Jackson-Cross, 402 Pa.Super 492, 501, 587 A.2d 727, 732 (1991)).
For example, in Pocono International Raceway v. Pocono Produce, 503 Pa. 80, 468 A.2d 468 (1989), the plaintiff owned a tunnel damaged by a collision with a truck owned by the *216defendant on June 15 or June 18, 1978. In October, 1978, the tunnel was closed and sealed until April 1979. When the tunnel was re-opened in April of 1979, the plaintiff learned that it had collapsed. The plaintiff then sued the truck’s owner, and claimed that the statute of limitations was tolled by the discovery rule. We held as a matter of law that the plaintiff failed to exercise diligence in discovering that defendant’s produce truck caused damage to its tunnel within the two year limitations period. We opined:
In the present case, as a matter of law, the cause of action was discoverable by the exercise of diligence in the use of means within the reach of Raceway, and, as such, no equitable exception to the statutory limitation is warranted.... This is not the sort of blameless ignorance which compels the application of the discovery rule ...
Id. at 86, 468 A.2d at 471.
Thus, we have not hesitated to find as a matter of law that a party has not used reasonable diligence in ascertaining the cause of an injury thus barring the party from asserting their claim under the discovery rule.
In evaluating whether the trial court committed an error of law or an abuse of discretion in the instant case, we are mindful of several well-established principles of law. We note that the discovery rule is an exception to the general rule that the statute of limitations begins to run as soon as the right to institute and maintain a suit arises. Pocono, 503 Pa. at 84, 468 A.2d at 471. Therefore, one claiming the benefit of the exception bears the burden of establishing that she falls within it. As we stated in Pocono: “Once the prescribed statutory period has expired, the party is barred from bringing suit unless it is established that an exception to the general rule applies which acts to toll the running of the statute.” Id. at 85, 468 A.2d at 471. Thus, it is the Appellant’s burden to establish that she is entitled to the discovery rule exception.
In Bcmmgart, the Opinion in Support of Reversal sets forth the definition of what constitutes reasonable diligence:
*217Reasonable diligence is just that, a reasonable effort to discover the cause of an injury under the facts and circumstance present in the case. Long ago we recognized that “[tjhere are few facts which diligence cannot discover, but there must be some reason to awaken inquiry and direct diligence in the channel in which it would be successful. This is what is meant by reasonable diligence.” Deemer v. Weaver, 324 Pa. 85, 90, 187 A. 215, 217 (1936) (quoting Madole v. Miller, 276 Pa. 131, 137, 119 A. 829, 831 (1923)). Reasonable diligence is an objective, rather than a subjective standard. Under this standard, the plaintiffs actions must be evaluated to determine whether he exhibited “those qualities of attention, knowledge, intelligence and judgment which society requires of its members for the protection of their own interests and the interests of others.” Burnside v. Abbott Laboratories, 351 Pa.Super. 264, 292, 505 A.2d 973, 988 (1985) (quoting Petri v. Smith, 307 Pa.Super. 261, 271, 453 A.2d 342, 347 (1982)). See also Restatement (Second) of Torts § 283 comment b. Despite the objective nature of the reasonable diligence standard, “[i]t is sufficiently flexible, however, to take into account difference[s] between persons and their capacity to meet certain situations and the circumstances confronting them at the time in question.” Burnside, 351 Pa.Super. at 292, 505 A.2d at 988 (quoting Petri, 307 Pa.Super. at 271-72, 453 A.2d at 347). Thus, this case law teaches that a plaintiff is not under an absolute duty to discover the cause of his illness. Instead, he must exercise only the level of diligence that a reasonable man would employ under the facts and circumstances presented in a particular case.
Opinion in Support of Reversal at 207, 666 A.2d at 244.
Our case-law further enlightens us on what is reasonable under the facts of a particular case. It is well settled that the statute of limitations is not tolled by mistake or misunderstanding. Pocono Intern. Raceway, 503 Pa. at 84, 468 A.2d at 471; Nesbitt v. Erie Coach Co., 416 Pa. 89, 93, 204 A.2d 473, 475 (1964). Aso, a diligent investigation may require one to seek further medical examination as well as competent legal *218representation. Murray v. Hamot Medical Center, 429 Pa.Super. 625, 634-35, 633 A.2d 196, 201 (1993), appeal denied, 540 Pa. 632, 658 A.2d 796 (1994) (citing Souders v. Atlantic Richfield Co., 746 F.Supp. 570, 573 (E.D.Pa.1990) citing United States v. Kubrick, 444 U.S. 111, 123, 100 S.Ct. 352, 360, 62 L.Ed.2d 259 (1979)).
With these principles in mind, we cannot say that the trial court committed an error of law or an abuse of discretion in granting Appellees’ motion for summary judgment. It is clear that reasonable minds would not differ as to whether the decedent exercised reasonable diligence in discovering the cause of his cancer in the instant case. Here, the decedent was first diagnosed with lung cancer in 1981. The record indicates that there was ample evidence to support a diagnosis of asbestos-related lung cancer at that time. However, Mr. Cochran did not seek additional legal or medical help to ascertain the precise cause of his cancer until March of 1985. Appellant’s sole explanation for this nearly four year lapse is the assertion that the decedent believed that his cancer was caused by his smoking habit and he, accordingly, stopped smoking. There is no medical evidence in the record to support the decedent’s mistaken belief that his cancer was caused solely by his smoking.
Appellant in essence contends that her husband mistakenly diagnosed the cause of his cancer as smoking related rather than asbestos related, and did not discover the real cause until 1985 after a second hospitalization. Unfortunately, under our case law cited supra, the decedent’s mistaken belief cannot toll the statute of limitations for the four year period between 1981 and 1985. The record amply demonstrates that the asbestos related nature of the cancer was apparent in June of 1981, and that the decedent failed to seek additional legal and medical help to ascertain the actual cause of his injury until March of 1985.
Here, the decedent waited four years before diligently pursuing the cause of his illness. Therefore, we agree with the en banc panel of the Superior Court that reasonable minds *219could not differ as to the decedent’s lack of reasonable diligence rendering this case suitable for summary judgment. The decedent’s failure to ascertain the cause of his injury was the result of “somnolence,” rather than “blameless ignorance.” See Ayers v. Morgan, 397 Pa. 282, 291, 154 A.2d 788, 792 (1959), and Pocono Intern. Raceway, 503 Pa. at 86, 468 A.2d at 471. Accordingly, the trial court did not commit an error of law or an abuse of discretion in entering a grant of summary judgment.
The Dissent accuses us of having committed two errors. These accusations warrant a brief response. First, we are charged with having overlooked medical history information contained in the decedent’s medical records. The Dissent asserts that these medical records create material facts that make summary judgment inappropriate in this case. However, we believe that the Dissent is torturing routine medical history information in an attempt to create an issue of material fact. The medical history quoted by the Dissent merely reveals that Mr. Cochran’s doctors noted that he was a smoker, and recommended that he stop smoking. This information is in the nature of routine medical history taken from any patient. See, e.g., Reproduced Record at 203 (“patient is a heavy smoker” under “Indications”); R.R. at 206 (“The patient smoked sixty packs a year, and quit last week.” under “Social History”); R.R. at 233 (“history of heavy cigarette abuse” under “Past Medical History”); R.R. at 252 (“He is a heavy smoker, no significant alcohol history”); R.R. at 261 (“He smokes 1 to 2 packs of cigarettes per day and is known to drink from 1 to 2 fifths of ethanol per week” under “Social History”). Nowhere in the record is the decedents’s smoking causally related to his lung cancer. Quite simply, these routine medical entries do not constitute a diagnosis that the decedent’s smoking caused his cancer in 1981. Thus, we cannot agree with the Dissent that “it is apparent that the appellant and his physician concluded in 1981 that the lung cancer was caused by smoking.” Dissent at 222. Accordingly, while the Dissent argues that we are acting as fact-finder, it would appear that the Dissent is actually combing the *220record in a somewhat frantic attempt to manufacture a genuine issue of material fact where none exists.
Second, the Dissent accuses us of creating a heightened standard for establishing due diligence. Apparently, the Dissent would be in favor of a “no diligence” rule allowing anyone with a good faith, even if mistaken, belief to claim the discovery rule exception. Despite the apparent benevolence of such an approach, it is not supported by our case-law. Our cases firmly establish that the “reasonable diligence” standard has some teeth. A person claiming the discovery rule exception has the burden of establishing that he pursued the cause of his injury with “those qualities of attention, knowledge, intelligence and judgment which society requires of its members for the protection of their own interests and the interests of others.” Burnside v. Abbott Laboratories, 351 Pa.Super. 264, 292, 505 A.2d 973, 988 (1985) (quoting Petri v. Smith, 307 Pa.Super. 261, 271, 453 A.2d 342, 347 (1982). As discussed supra, this standard may require a party to obtain additional legal and medical advice. Also, a party may not rely on mistake or misunderstanding to toll the limitations period. The approach of the Dissent would dramatically expand the discovery rule and open the flood gates to allow anyone with a good faith lack of diligence to claim benefit of the rule. The standard proposed by the Dissent would severely erode the finality of our statute of limitations, and that would truly be a “grievous error.”
For the reasons set forth above, we affirm the order of the en banc panel of the Superior Court.
CAPPY, J., files a dissenting opinion in which NIX, C.J., has joined. MONTEMURO, J., is sitting by designation.. The identical issue also appears in the companion case of Baumgart v. Keene, 542 Pa. 194, 666 A.2d 238 (1995), in which the Court, on somewhat different facts, was equally divided.