Calumniae non temere credundum

Yet this is not an insignificant or a simple thing, as one might suppose; it requires much skill, no little shrewdness, and some degree of close study.

For slander would not do so much harm if it were not set afoot in a plausible way, and it would not prevail over truth, that is stronger than all else, if it did not assume a high degree of attractiveness and plausibility and a thousand things beside to disarm its hearers.