Here are some things that really stuck out to me as Ryle dealt with his first point:
"...the vast majority of children are manifestly not trained in the way they should go, for when they grow up to man's estate they do not walk with God.
Now, how shall we account for this state of things? The plain truth is, the Lord's commandment in our text is not regarded; and therefore the Lord's promise in our text is not fulfilled."
If we are to regard this command, Ryle says:
"Reject them [his following points] not because they are blunt and simple; despise them not because they contain nothing new. Be very sure, if you would train your children for heaven, they are hints that ought not be lightly set aside."
And that's it,
the way our children should go, the way our children must go, the way our children were intended to go is with God.
They have been placed in our care that we might point the way to God and train them for heaven.