Verse 17. That no man might buy or sell - Such edicts have been published long since against the poor Vaudois. But he that had the mark, namely, the name of the first beast, or the number of his name - The name of the beast is that which he bears through his whole duration; namely, that of Papa or Pope: the number of his name is the whole time during which he bears this name. Whosoever, therefore, receives the mark of the beast does as much as if he said expressly, "I acknowledge the present Papacy, as proceeding from God;" or, "I acknowledge that what St. Gregory VII. has done, according to his legend, (authorized by Benedict XIII.,) and what has been maintained in virtue thereof, by his successors to this day, is from God." By the former, a man hath the name of the beast as a mark; by the latter, the number of his name. In a word, to have the name of the beast is, to acknowledge His papal Holiness; to have the number of his name is, to acknowledge the papal succession. The second beast will enforce the receiving this mark under the severest penalties.
Verse 18. Here is the wisdom - To be exercised. "The patience of the saints" availed against the power of the first beast: the wisdom God giveth them will avail against the subtilty of the second. Let him that hath understanding - Which is a gift of God, subservient to that wisdom. Count the number of the wild beast - Surely none can be blamed for attempting to obey this command. For it is the number of a man - A number of such years as are common among men. And his number is six hundred and sixty-six years - So long shall he endure from his first appearing.