But this, thou wilt say, is the very point in dispute--whether any foreknowing is possible of things whose occurrence is not necessary.

For here there seems to thee a contradiction, and, if they are foreseen, their necessity follows; whereas if there is no necessity, they can by no means be foreknown; and thou thinkest that nothing can be grasped as known unless it is certain, but if things whose occurrence is uncertain are foreknown as certain, this is the very mist of opinion, not the truth of knowledge.

For to think of things otherwise than as they are, thou believest to be incompatible with the soundness of knowledge.
'Now, the cause of the mistake is this--that men think that all knowledge is cognized purely by the nature and efficacy of the thing known.

Whereas the case is the very reverse: all that is known is grasped not conformably to its own efficacy, but rather conformably to the faculty of the knower.

An example will make this clear: the roundness of a body is recognised in one way by sight, in another by touch.