As a result of a general defect of nature, we are either more confident or more fearful of unusual and unknown things.
It is not these well-fed long-haired men that I fear, but the pale and the hungry-looking.
Men's minds tend to fear more keenly those things that are absent.
In extreme danger fear feels no pity. [Lat., In summo periculo timor miericordiam non recipit.]
Go on, my friend, and fear nothing; you carry Caesar and his fortune in your boat.