(dissenting, with whom Hennessey, C.J., joins). The plaintiffs’ business involves the installation of electrical wiring connecting horns, sprinklers, alarm boxes, bells, and sirens to a control box, which in turn is connected to an electrical power supply. According to uncontradicted testimony *250in the Superior Court, sophisticated modem alarm systems perform such functions as overriding elevator control systems, closing electromagnetic doors, and reversing air circulation systems, The purpose of the wiring installed by the plaintiffs is to transmit the electrical power required to sound the horns, bells, and sirens, and to activate the sprinklers and other protective devices. Yet, the court denies that the plaintiffs are “person[s], firm[s] or corporation^] . . . engage[d] in . . . the business of installing wires ... for carrying . . . electricity for . . . power purposes” within the meaning of G. L. c. 141, § 1 (1984 ed.). The court ignores the principle, to which it purports to adhere, ante 238, 242, (1985), that “[statutory language is the principal source of insight into Legislative purpose.” Commonwealth v. Lightfoot, 391 Mass. 718, 720 (1984). I would hold that the plaintiffs come within the meaning of G. L. c. 141, § 1, and that, because they are not “companies incorporated for the transmission of intelligence by electricity,” they do not come within the exemption from c. 141, provided by c. 141, § 7. As a consequence, I would further hold, as did the Appeals Court, that Rule 2.2 of the Rules and Regulations of the Board of State Examiners of Electricians is a valid exercise of the examiners’ mie making power granted by G. L. c. 141, § 2. Any concern of the court, no matter how legitimate it may be, that such a holding would grant electricians a legal monopoly, see ante at 249, does not justify the tortured construction that the court gives the plain language of the statute. If, through G. L. c. 141, § 1, the Legislature has granted electricians a monopoly, the Legislature may remedy that situation if it chooses to do so.
The court reasons that, since the Legislature originally used the words “light, heat or power” in legislation governing the sale of electric power by utilities, those words acquired “a specialized legislative meaning, relating to the sale of electric power by utilities.” Ante at 242. The court speaks of “the utility context in which the Legislature intended the statute to apply,” ante at 247, and of the Legislature’s intent “to grant power to the examiners only over companies in the business of installing wires which carry or use electricity as a product, *251for light, heat or power purposes, but not over the infinitely broader spectrum of companies in the business of supplying other products that merely use electricity as a source, for light, heat or power” (emphasis in original). Therefore, stating that “[a]larm system installers do not install wires to carry electricity; they install wires to provide alarm systems,” ante at 243, the court concludes that G. L. c. 141, § 1, does not apply to the plaintiffs.
That reasoning seems to suggest that G. L. c. 141 applies only to those who install wires for the purpose of carrying electricity they have produced, i.e., utilities, and perhaps to their employees. Surely that was not the intent of the Legislature. If the court does not mean that, it must mean, at least, that G. L. c. 141 applies to those in the business of installing electrical wires so that a building will have electrical wiring, but not to those who install electrical wires only in connection with the installation of some other product, like an alarm system. The statutory language does not support such a distinction. Alarm installers install wires “for carrying electricity for . . . power purposes,” and they get paid to install those wires. Therefore, despite the court’s statement that “[a]larm system installers do not install wires to carry electricity; they install wires to provide alarm systems,” ante at 243, alarm installers are persons “engaged in . . . the business of installing wires ... for carrying . . . electricity for . . . power purposes” as provided by G. L. c. 141, § 1.
The court’s decision is not justified by its expressed reluctance to interpret G. L. c. 141 in a way that would result in examiners’ having authority to regulate “those who are in the business of supplying, delivering and installing such mundane items as washing machines, televisions, and toasters, since they, too, have wires that are connected to a source of electricity through a wall outlet.” Ante at 249. The statute prohibits participation without a license in “the business of installing wires, conduits, apparatus, fixtures or other appliances for carrying or using electricity for light, heat or power purposes.” Plugging an appliance into an outlet is not installation. Running wires between locations in a building, as is typical in burglar and *252fire alarm systems, on the other hand, is installation. “[RJeason and common sense are not to be abandoned” when we interpret statutes, van Dresser v. Firlings, 305 Mass. 51, 53 (1940).
To bolster its conclusion, the court improperly relies on actions taken by the examiners since St. 1915, c. 296 (now G. L. c. 141), was enacted. Stating that, “in 1948, the examiners asked the Attorney General whether the wires and apparatus used in television installation constituted the use of ‘electricity for light, heat or power purposes,’ ” ante at 245, and asserting that, in 1975, by introducing legislation designed to amend G. L. c. 141, § 1, the examiners demonstrated their concern that “ Tight, heat or power purposes’ ” was not broad enough to authorize rule 2.2, ante at 246, the court concludes that “the examiners apparently have never been convinced that regulations such as those involved here were within their statutory mandate.” Ante at 245. By relying on those actions, the court unwisely ignores our previously expressed policy to “not draw the inference that the [agency] believed it was without the power requested from the fact that the legislation was introduced. Such an inference would be merely speculative and might serve to chill the agency’s freedom to seek ‘clarifying legislation on a genuinely debatable point of agency procedure . . . .’ Wong Yang Sung v. McGrath [339 U.S. 33, 47-48, modified, 339 U.S. 908 (1950)]. Cf. Commonwealth v. Woods Hole, Martha’s Vineyard & Nantucket S.S. Auth., 352 Mass. 617, 619-620 (1967).” Massachusetts Comm’n Against Discrimination v. Liberty Mut. Ins. Co., 371 Mass. 186, 194 (1976).
Similarly, the court’s reliance on the examiners’ failure to attempt to enforce regulations concerning the installation of alarms until 1969 does not help the court. It may be that advances in alarm technology or other considerations prompted the examiners to exercise that authority for the first time in 1969, but in any event, “[authority actually granted by [the Legislature] . . . cannot evaporate through lack of administrative exercise.” FTC v. Bunte Bros., 312 U.S. 349, 352(1941). See Brooks v. Architectural Barriers Bd., 14 Mass. App. Ct. 584, 588-589 (1982). The examiners now purport to possess *253the authority to regulate the installation of alarms, and that assertion of authority deserves respect. White Dove, Inc. v. Director of the Div. of Marine Fisheries, 380 Mass. 471, 477 (1980).
Just as the examiners’ actions lend no support to the court, neither can the failure of recent Legislatures to adopt proposed amendments to G. L. c. 141 lend the court aid. The court infers from the Legislature’s failure to enact several proposed bills that there has been legislative opposition to the examiners’ having the authority they now claim. But that is not a valid inference. “[N]o one knows why the legislature did not pass the proposed measures. . . . The practicalities of the legislative process furnish many reasons for the lack of success of a measure other than legislative dislike for the principle involved in the legislation.” Irwin v. Ware, 392 Mass. 745, 773 (1984), quoting Berry v. Branner, 245 Or. 307, 311 (1966). Furthermore, inquiry into the preference of Legislatures since 1915 is off the mark. The critical issue is what the Legislature that enacted the statute intended — not what subsequent Legislatures thought of proposed amendments to the statute. Failure of subsequent legislative bodies to adopt proposed amendments “ ‘has no persuasive significance’ with reference to the intent of the Legislature which passed the original bill. Devlin v. Commissioner of Correction, 364 Mass. 435, 442-443 (1973). United States v. Wise, 370 U.S. 405, 411 (1962). ‘[T]he views of a subsequent [Legislature] form a hazardous basis for inferring the intent of an earlier one.’ United States v. Price, 361 U.S. 304, 313 (1960). Wong Yang Sung v. McGrath, 339 U.S. 33, 47-48, modified, 339 U.S. 908 (1950). Helvering v. Hallock, 309 U.S. 106, 119-121 (1940).” Massachusetts Comm’n Against Discrimination v. Liberty Mut. Ins. Co., supra at 193-194.
It is true, as the court states, that G. L. c. 141, § 5, renders G. L. c. 141 a penal statute, and that, for that reason, we must resolve in favor of criminal defendants any reasonable doubt about the statute’s meaning. But the meaning of the statute is clear. The plaintiffs engage in the business of installing wires *254to carry electricity for power purposes, and therefore they are required to be licensed and to otherwise comply with rule 2.2.
I would vacate the judgment entered in the Superior Court, and I would remand the case to that court for the entry of a judgment declaring valid rule 2.2, as codified in 237 Code Mass. Regs. § 4.02 (3) (1981), and declaring G. L. c. 141, § 7 (1984 ed.), inapplicable to the plaintiffs.