Tenacious Heart

Deuteronomy 4:9
Only be careful, and watch yourselves closely so that you do not forget the things your eyes have seen or let them slip from your heart as long as you live. Teach them to your children and to their children after them.
This is an incredible chapter. Moses must have had the crowd on their feet here.
It begins with "Hear, O Israel." He explains that the keeping of the commandments will give Israel a good reputation among nations, a rep for being wise and understanding. He mentions two of the essential, unique qualities of Israel in the context of the world:
No other gods stay as close to their nations as Yahweh does to Israel.
No other nation has the advantage of the laws given to Israel.
But these blessings will mean nothing if Israel neglects to do its part, which is to remember what God has done and hold those things in their heart. Further, they must teach those things to their children.
Nor can I let the things God has taught me slip from my heart. There's the matter of the mind first, making sure I don't forget. Our inclination is to forget, and be overwhelmed by what is present. Second, don't let the truths slip. They slip if we don't consciously hold on.