It is easy to despise what you cannot get

A wild boar was sharpening his tusks upon the trunk of a tree in the forest when a fox came by and asked, Why are you doing that, pray? The huntsmen are not out today and there are no other dangers at hand that I can see. True, my friend, replied the Boar, but the instant my life is in danger, I shall need to use my tusks. There will be no time to sharpen them then.

Distrust unsolicited advice.

In serving the wicked, expect no reward, and be thankful if you escape injury for your pains.

Appearances are deceiving.

Better be wise by the misfortunes of others than by your own.

He that is neither one thing nor the other has no friends.