“Therefore do not seek to understand in order to believe, but believe that thou mayest understand.”
Ergo noli quaerere intelligere ut credas, sed crede ut intelligas.
Tractates on the Gospel of John; tractate XXIX on John 7:14-18, §6 A Select Library of the Nicene And Post-Nicene Fathers of the Christian Church Volume VII by St. Augustine, chapter VII (1888) as translated by Philip Schaff http://www.ccel.org/ccel/schaff/npnf107.iii.xxx.html.
Compare: Anselm of Canterbury: "Nor do I seek to understand that I may believe, but I believe that I may understand".