Institutio Oratoria

Above all we must see that we do not contradict ourselves, a slip which is far from rare on the part of spinners of fiction: for some things may put a most favourable complexion on portions of our case, and yet fail to agree as a whole. Further, what we say

In either case the orator should bear clearly in mind throughout his whole speech what the fiction is to which he has committed himself, since we are apt to forget our falsehoods, and there is no doubt about the truth of the proverb that a liar should have a good memory.