In his 1912 encyclical Singulari quadam (not previously referenced on this site), Pope St. Pius X writes:
No matter what the Christian does, even in the realm of temporal goods, he cannot ignore the supernatural good. Rather, according to the dictates of Christian philosophy, he must order all things to the ultimate end, namely, the Highest Good.
That Highest Good is, in a word, God. (In a longer word, beatitude, but it turns out to be the same thing. We're capax Dei, baby!)
The idea of the "Highest Good" fits right in with the idea of a "hierarchy of goods," which goes back to Aristotle at least, and which allows us to define moral evil as the choice of a lesser good in place of a greater good. (The idea that we always choose good, or at least what looks good to us, goes back to Plato at least.)
So the overall idea is of an ordering of goods, from the lowest to the highest. The ordering is likely only partial, since it's likely that two goods can be equivalently good (a Phillies victory and a Mets loss, for example). And sitting at the top as the good greater than which none can conceive is God.
But that idea is false. The Highest Good isn't a good, It's Goodness. When we sin, we don't choose a lesser good in place of God -- what does it actually mean to "choose God," anyway? -- we choose a lesser good in place of what God tells us is a greater good.
In these terms, the old Masonic symbol might be onto something:
God is above all goods, but He is not part of or even the limit of them.
O Lord God, I love you above all things and I love my neighbor for your sake because you are the highest, infinite and perfect good, worthy of all my love. In this love I intend to live and die. Amen.
Domine Deus, amo te super omnia et proximum meum propter te, quia tu es summum, infinitum, et perfectissimum bonum, omni dilectione dignum. In hac caritate vivere et mori statuo. Amen.
Here God isn't merely the summum bonum, He's also infinítum et perfectíssimum. Speaking of the Highest and Infinite and Perfect Good makes it a bit harder to mistake God as only the best of many or as in any way directly comparable to anything.
When the Pope tells us we must order all things to the Highest Good, we shouldn't understand him as meaning that we "choose God" in the same sense we might choose scrambled eggs or choose to be kind.
Nonisity, to have or want nothing but God, doesn't necessarily mean just me 'n' Jesus sitting on the ground in rags. That would make discipleship a matter of externals. We don't obtain the Highest Good instead of lesser goods, but through them (particularly the virtues and gifts of the Holy Spirit).
So what? So when we as Christians offer Christ to others, we offer Him through created goods. There's an upside to this, since it's easier to accept created goods than the mandate to strip to rags and sit on the ground. There's also a downside, since it's easy to take your eyes off Him and look instead at the created goods.