[131] and this is a matter within the knowledge of almost every one from his daily experience. For, when we thoroughly understand what we are saying, then our speech rejoices and exults, and is rich in most emphatic and appropriate expressions, with which, using great copiousness and fluency of unhesitating diction, it sets before the hearer what it desires to exhibit to him in a most evident and efficient manner. But when the comprehension of the conceptions is doubtful, then the speech stumbles and exhibits a great deficiency of suitable and felicitous expressions, and speaks very inappropriately; on which account it is tedious and wearisome and wanders about, and instead of persuading its hearers it pains their ears.