Seneca, Moral Epistles 12.6-8
“The whole of our life is made of parts: it has large circles with smaller ones traced inside. There’s one circle that embraces and contains all the rest–it runs from our birth to our final day. There’s another that encloses our adolescence and another that contains all of childhood in its circuit. Then there’s the annual course that contains all the parts of time in its turn, which, when multiplied, contains all of life. The month is enclosed by a narrower ring while the day has the smallest circle. Yet even the day goes from its beginning to end, from sunrise to sunset.
This is why Heraclitus, who earned that nickname “the obscure” for his rhetorical style, said, “each day is the same as the rest. People explain this in various ways. One says that a day is equal in is number of hours. This isn’t a lie, if we think that a day is 24 hours hours. In that case, all days are necessarily equal because the night takes what the day loses.
Another claims that one day is the same as another in its appearance, since even the longest period of time has nothing more than what you can find in a day. It has light and night and the alternation of days into eternity makes these more numerous, not really different by expanding or contracting the count. And so, each day should be organized as if it continues and completes a sequence, and closes the circuit of a life.”
Tota aetas partibus constat et orbes habet circumductos maiores minoribus. Est aliquis, qui omnis conplectatur et cingat; hic pertinet a natali ad diem extremum. Est alter, qui annos adulescentiae cludit. Est qui totam pueritiam ambitu suo adstringit. Est deinde per se annus in se omnia continens tempora, quorum multiplicatione vita conponitur. Mensis artiore praecingitur circulo. Angustissimum habet dies gyrum, sed et hic ab initio ad exitum venit, ab ortu ad occasum.
Ideo Heraclitus, cui cognomen fecit orationis obscuritas, “Unus,” inquit, “dies par omni est.” Hoc alius aliter excepit. Dixit enim parem esse horis, nec mentitur; nam si dies est tempus viginti et quattuor horarum, necesse est omnes inter se dies pares esse, quia nox habet, quod dies perdidit. Alius ait parem esse unum diem omnibus similitudine; nihil enim habet longissimi temporis spatium, quod non et in uno die invenias, lucem et noctem, et in aeternum dies vices plures facit istas, non alias contractior, alias productior. Itaque sic ordinandus est dies omnis, tamquam cogat agmen et consummet atque expleat vitam.

Personally, I am partial to circles that do not end…