Plutarch, Quomodo quis suos in virtute sentiat profectus
Frank Cole Babbitt, Ed.

But as for us, we observe that there are degrees in every kind of evil, and especially in the indeterminate and undefined kind that has to do with the soul. (In the same way also there are different degrees of progress produced by the abatement of baseness like a receding shadow, as reason gradually illuminates and purifies the soul.) We do not, therefore, think that consciousness of the change is unreasonable in the case of persons who are, as it were, making their way upward out of some deep gorge, but that there are ways in which it can be computed. Of these I beg you to consider the first without further preface. Just as men sailing out into the open sea calculate their run by the time elapsed in conjunction with the strength of the wind, reckoning how much distance, after spending a certain time, while carried onward by a certain force, they are likely to have accomplished ; so too in philosophy a man may take for himself as a proof that he is gaining ground the uniformity and continuity of his course, which makes on the way no frequent halts, followed by leaps and bounds, but smoothly and regularly forges ahead, and goes through the course of philosophic reasoning without mishap. For the lines :

If even small upon the small you place And do this oft,¹

are not merely well put in regard to the increase of [p. 409] money, but they apply to everything, and especially to advancement in virtue, since reason thereby gains the aid of constant and effective habit. But the variation and obtuseness often shown by students of philosophy not only cause delays and stoppages in their progress on the road to knowledge, but also bring about retrogressions, since vice always makes an onset on the man who yields ground by loitering, and carries him backward in the opposite direction. Mathematicians tell us that the planets, when their forward movement ceases, become for the moment stationary, but in the study of philosophy there is no intermission when progress halts, nor any such thing as remaining stationary, but Nature, being never free from motion of some sort, is wont to move up or down, as though suspended on a balance, and to be swayed by the better motives, or else under the influence of the contrary motives it moves rapidly towards what is worse. If therefore you follow the advice given by the god in the oracle, to ‘fight the Cirrhaeans all days and all nights,’ and are conscious that you likewise in the daytime and the nighttime have always carried on an unrelenting warfare against vice, or at least that you have not often relaxed your vigilance nor constantly granted admission to divers pleasures, recreations, and pastimes, which are, as it were, envoys sent by vice to treat for a truce, it is then quite probable that you may go on with good courage and confidence to what still remains.