If the incapacity arose from natural infirmity, or unavoidable accident, you ought to acquit. But, if it was voluntary, you ought to convict. The intention with which the intoxication was produced, whether with a direct view to disqualify, or not, is not essential to the conviction. For it was his duty, not only not to disqualify himself, but to take reasonable care to preserve himself in a state sit for doing his duty.