It can be proved to him, by a very simple analysis of some of his spare elements, that every Sunday, when he does his duty faithfully, he uses up more phosphorus out of his brain and nerves than on ordinary days.

But then he had his choice whether to do his duty, or to neglect it, and save his phosphorus and other combustibles.
It follows from all this that THE FORMATION OF HABITS ought naturally to be, as it is, the special characteristic of age.

As for the muscular powers, they pass their maximum long before the time when the true decline of life begins, if we may judge by the experience of the ring.

A man is "stale," I think, in their language, soon after thirty,--often, no doubt, much earlier, as gentlemen of the pugilistic profession are exceedingly apt to keep their vital fire burning WITH THE BLOWER UP.
-- So far without Tully.

But in the mean time I have been reading the treatise, "De Senectute." It is not long, but a leisurely performance.