Epistle LXXII. On business as the enemy of philosophy

The subject concerning which you question me was once clear to my mind, and required no thought, so thoroughly had I mastered it. But I have not tested my memory of it for some time, and therefore it does not readily come back to me. I feel that I have suffered  the fate of a book whose rolls have stuck together by disuse; my mind needs to be unrolled, and whatever has been stored away there ought to be examined from time to time, so that it may be ready for use when occasion demands. Let us therefore put this subject off for the present; for it demands much labour and much care. As soon as I can hope to stay for any length of time in the same place, I shall then take your question in hand. For there are certain subjects about which you can write even while traveling in a gig, and there are also subjects which need a study-chair, and quiet, and seclusion.

Seneca Epistles 66-92, Translation by Richard Gummere. Loeb Classical Library.