A friend is called a foot, on account of its service in going about for us, since he is as it were ready for our use.
It goes on: “And if thine eye offend thee, pluck it out: it is better for thee to enter into the kingdom of God with one eye, than having two eyes to be cast into hell fire; where their worm dieth not, and the fire is not quenched.”
A friend who is useful, and anxious, and sharp in perception, is called an eye.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).