The tradition places this teaching at a hinge point — spoken at the very close of one age, just before a harder one is said to begin. Read that timing as more than decoration and it becomes a specific claim: the medicine was handed out just ahead of the disease, not after it had already taken hold.
Whatever one makes of the timing, the reason the teaching keeps being reached for has nothing to do with dates. It is reached for the way a physician is kept nearby rather than visited once and forgotten, the way an uncertain student keeps a steady teacher close rather than filing away one piece of advice. A page read once and shelved is a different object from a page returned to on the specific evening it is needed.
One reader of the last century, writing from inside a genuinely difficult public life, described going back to this text specifically on the days doubt or hardship pressed hardest — not for an answer to a question, but because some line in it, almost every time, met the actual weight of the day and gave back steadiness rather than distraction. That is a narrower promise than instant relief, and a more durable one: not that difficulty stops arriving, but that a hard day stops being able to fully knock the ground out from under someone who keeps this close.
Which is the whole reason a reading like this one exists at all — not to file an old teaching away as history, but to keep it exactly as available on an ordinary difficult Tuesday as it was, once, on the worst morning of someone else's life.