Constant and frequent questioning is the first key to wisdom. … For through doubting we are led to inquire, and by inquiry we perceive the truth.

[Prima sapientiae clavis definitur, assidua scilicet seu frequens interrogatio … Dubitando enim ad inquisitionem venimus; inquirendo veritatem percipimus.]

Peter Abelard (1079-1142) French philosopher, theologian, logician [Pierre Abélard]

Sic et Non, Prolog [tr. Graves (1918)]