we had such men as Cassius, though of an ill temper, but critical, we would have made quite some strides against all superstition. In an address to Brutus, he had this to tell him
It is the opinion of our sect[ Epicurian philosophy] that not all that we feel or see is real and true;but that sense is a most slippery and deceitful thing, and the mind yet more quick and subtle to put the sense in motion and affect it with every kind of change upon no real occasion of fact; just as an impression is made upon wax; and the soul of man, which has itself both what imprints and what is imprinted on, may most easily, by its own operations, produce and assume every variety of shape and figure.
[..] It is its nature to to be ever in motion and its motion is fantasy or conception.
[…]But that there should be any such things as supernatural beings, or if there were, that they should have human shape or voice or power that can reach us, there is no reason for believing, though I confess I could wish that there were such beings, that we might not rely upon our arms only and our horses and our navy, all which are numerous and powerful, but might be confident of the assistance of gods also, in this our most sacred and honourable attempt.
Cassius to Brutus in Plutarch Lives of the Noble Grecians and Romans