De Agricultura

Now, the horses are appetite and passion, the one being male and the other female. On this account, the one giving itself airs, wishes to be unrestrained and free, and holds its head erect, as a male animal naturally does; and the other, not being free, but of a slavish disposition, and rejoicing in all kinds of crafty wickedness, devours the house, and destroys the house, for she is female. And the rider and charioteer is one, namely the mind. When, indeed, he mounts with prudence, he is a charioteer; but when he does so with folly, then he is but a rider.