De Agricultura

When a man has acquired this, and thoroughly comprehends it, and is entirely acquainted with the powers of his adversaries, it will be his task to war against

the company of contentious sophists, for there is good hope that such a man may conquer; but he who is still impeded by the cloud of ignorance in front of him, and who is not yet able to pour forth the light of knowledge, may safely remain at home; that is to say, it is well for him not to enter into a contest with respect to those matters with which he is not thoroughly acquainted, but he had better rest and keep quiet.