Origen
Catena Aurea · Markusevangelium 10
And they brought young children to him, that he should touch them: and his disciples rebuked those that brought them. But when Jesus saw it, he was much displeased, and said unto them, Suffer the little children to come unto me, and forbid them not: for of such is the kingdom of God. Verily I say unto you, Whosoever shall not receive the kingdom of God as a little child, he shall not enter therein. And he took them up in his arms, put his hands upon them, and blessed them.
(Matt. tom. xv. 7) If any of those who profess to hold the office of teaching1 in the Church should see a person bringing to them some of the foolish of this world, and low born, and weak, who for this reason are called children and infants, let him not forbid the man who offers such an one to the Saviour, as though he were acting without judgment. After this He exhorts those of His disciples who are already grown to full stature to condescend to be useful to children, that they may become to children as children, that they may gain children; for He Himself, when He was in the form of God, humbled Himself, and became a child. On which He adds: For of such is the kingdom of heaven. (1 Cor. 9:22)