Augustine of Hippo — as excerpted in the Catena Aurea on John 6:60-71

“(Tr. xxvii. s. 9) For we believed, in order to know. Had we wished first to know, and then to believe, we could never have been able to believe. This we believe, and know, that Thou art the Christ the Son of God; i. e. that Thou art eternal life, and that in Thy flesh and blood Thou givest what Thou art Thyself.”