Theophylact of Ohrid — as excerpted in the Catena Aurea on John 1:24-28

“(in loc.) Or it was, that our Lord was in the midst of the Pharisees; and they not knowing Him. For they thought that they knew the Scriptures, and therefore, inasmuch as our Lord was pointed out there, He was in the midst of them, i. e. in their hearts. But they knew Him not, inasmuch as they understood not the Scriptures. Or take another interpretation. He was in the midst of them, as mediator between God and man, wishing to bring them, the Pharisees, to God. But they knew Him not.”