Aquinas Contribution to the History of the Church

In the early church, what is the benefit that a child gets when they receive. Grace is something that affects intellects and wills. Revelation tells us that the church is always obligated to use the sacramental system for salvation. aquinas has probably one of the most robust psychologies that has ever existed in the history of the church. And so he can see why holy communion doesn't benefit a child when it comes to grace infusing the intellect or graceinfusing the will. So i moing to take him as making a pastoral argument based on psychology. Is i he can't find any sort of spiritual benefit in the intellect and the will, therefore there's no necessity for it?