Augustine of Hippo

(de Verb. Dom. s. 43) He knew Himself that His witness of Himself was true, but in compassion to the weak and unbelieving, the Sun sought for candles, that their weak sight might not be dazzled by His full blaze. And therefore John was brought forward to give his testimony to the truth. Not that there is such testimony really, for whatever witnesses bear witness to Him, it is really He who bears witness to Himself; as it is His dwelling in the witnesses, which moves them so to give their witness to the truth.