'Little Child' in the Bible

In that same hour he was full of joy in the Holy Spirit and said, I give praise to you, O Father, Lord of heaven and earth, because you have kept these things secret from the wise and the men of learning, and have made them clear to little children: for so, O Father, it was pleasing in your eyes.

Truly I say to you, Whoever does not put himself under the kingdom of God like a little child, will not come into it at all.