Letters 114.3

A man’s ability cannot possibly be of one sort and his soul of another. If his soul be wholesome, well-ordered, serious, and restrained, his ability also is sound and sober. Conversely, when the one degenerates, the other is also contaminated. Do you not see that if a man’s soul has become sluggish, his limbs drag and his feet move indolently? If it is womanish, that one can detect the effeminacy by his very gait? That a keen and confident soul quickens the step? That madness in the soul, or anger (which resembles madness), hastens our bodily movements from walking to rushing?

And how much more do you think that this affects one’s ability, which is entirely interwoven with the soul,—being moulded thereby, obeying its commands, and deriving therefrom its laws!

Seneca, Letters to Lucilius 114.3, translated by Richard Mott Gummere