And Jesus perceiving the thought of their heart,.... Not by any words he had heard; for the dispute was on the road, as they came along behind him; but as the omniscient God, who is the discerner of the thoughts and intents of the heart, he was privy to all their ambition, and the vanity of their minds, and to all their reasonings and debates: though he was before them, and out of the reach of hearing of them: and when he came to Capernaum, after having asked them what they disputed about by the way; he took a child and set him by him. The Ethiopic version reads, "before them", the disciples; and Matthew and Mark say, "he set him in the midst of them"; all which were true, Jesus sitting in the midst of them; so, that the child he set by him, was in the middle of them and before them; See Gill on Mat 18:2.