And don't forget this one: "suffer the little children to come unto me..."
The disciples tried to chase the little children away from Christ because they felt that such was beneath Christ's dignity.
Christ instead took the little children, touched them, and blessed them. I feel quite confident that the children had no intellectual idea of what was happening to them. I feel quite confident that their lives were changed (the life of St. Ignatius of Antioch certainly was!), and I feel quite confident that their ability or inability to understand what was happening when Christ laid his hands on them, touched them, and blessed them -- had nothing whatsoever to do with whether they received grace from Christ...
Christ does not want physical separation between himself and little children. He does not want them kept or chased away. They are incapable of the kind of willful apostasy and blasphemy that would make communion dangerous for them. So we bring them to be baptized, chrismated, churched, blessed, and especially, communed with His Body and Blood...