I am daily reminded of the truthfulness of this proverb.

Ọgbọ́n ní ńpẹ́ kó tó ran ẹni; wèrè kì í gbèé ran èèyàn; wèrè Ìbàdàn ló ran ará Ògbómọ̀ṣọ́.

“Only wisdom takes a long time to rub off on others; imbecility does not take long to affect others; it is the imbecility plaguing Ibadan people that rubbed off on the people of Ògbómọ̀ṣọ́.
-Yorùbá proverb

Explanation: Foolishness and ignorance is a social contagion that too few are inoculated against.