Chapter 27 — Part III: The Decalogue — The Fourth Commandment
Section 10. Moreover, no honour, no piety, no devotion can be rendered to God sufficiently worthy of Him, since love of Him admits of infinite increase. Hence our charity should become every day more fervent towards Him, who commands us to love Him with our whole heart, our whole soul, and with all our strength. The love of our neighbour, on the contrary, has its limits, for the Lord commands us to love our neighbour as ourselves.