But I would that you conserve what is truly yours and begin to do so at once. For, as our ancestors understood, "It is too late to be frugal when you have reached the dregs of the cast." There is not much left at the bottom, and only the worst of its content remains.
what is truly yours - Seneca is writing on the subject of time in this epistle and therefore the clause "what truly is yours" can be read in this context. There is a double-meaning here, however, and, for Seneca's purposes, a more important one. For the Stoic, "what is truly yours" refers to one's moral purpose, one's Virtue, the only thing that truly belongs to a person. Our own time is ours in the sense that we can always choose to spend whatever moments remain to us virtuously.
It is imperative that we begin to live virtuously immediately; for time is ours only in the sense of how we use it, not how long it will be. Indulging in Vice and neglecting Virtue and postponing the amendment of our ways until the last possible moment is akin to expecting to find quality wine at the bottom of the barrel. When we neglect and flee from Virtue for too long we run become a barrel that contains nothing left but the dregs of what could have been a fine wine.