Augustine of Hippo

(de Quæst. Ev. lib. ii. qu. 33.) But that which is said to have taken place not many days after, namely, that gathering all together he set out abroad into a far country, which is forgetfulness of God, signifies that not long after the institution of the human race, the soul of man chose of its free will to take with it a certain power of its nature, and to desert Him by whom it was created, trusting in its own strength, which it wastes the more rapidly as it has abandoned Him who gave it. Hence it follows, And there wasted his substance in riotous living. But he calls a riotous or prodigal life one that loves to spend and lavish itself with outward show, while exhausting itself within, since every one follows those things which pass on to something else, and forsakes Him who is closest to himself. As it follows, And when he had spent all, there arose a great famine in that land. The famine is the want of the word of truth.

It follows, And he began to be in want. Fitly did he begin to be in want who abandoned the treasures of the wisdom and the knowledge of God, and the unfathomableness of the heavenly riches. It follows, And he went and joined himself to a citizen of that country.