God made the world for the sake of mankind. If you can't see this, you are little different from an animal. Who looks up at heaven except human beings? Who admires the sun, the stars, and all God's works, except human beings? Who cultivates the earth and reaps its fruits? Who navigates the sea? Who has the fish, birds and beasts in his power - who except human beings? Therefore God made everything for mankind, because all things are given over into mankind's use. The philosopher's saw this correctly, but they did not see what follows - that God created mankind for himself. Since God set about for humanity's sake so great a work as the creation of the world, and since gave humanity's sake so great a work as the creation of the world, and since He gave humanity so much honour and power that it was supreme in the world, it was necessary in consequence, and a duty, that humanity would acknowledge God as the Author of such great blessings - He Who created mankind, and the world for mankind's sake - and that human beings should give to God the worship and honour He deserves.
(Source: Epitome of the Divine Institutes)