9 Let us then return to our subject. The perfection of righteousness is shown by the number forty. What is it to fulfil the number forty? To restrain one's self from the love of this world. Restraint from temporal things, that they be not loved to our destruction, is, as it were, fasting from this world. Therefore the Lord fasted forty days, and Moses, and Elias. He then who gave His servants the power to fast forty days, could He not fast eighty or a hundred? Why then did He not will to fast more than He had given His servants to do, but because in this number forty is the mystery of fasting, the restraint from this world?
What is this to say? What the Apostle says; “The world is crucified to me, and I to the world.” He then fulfils the number forty. And what does the Lord show? That because Moses did this, this Elias, this Christ, that this both the Law, and the Prophets, and the Gospel, teach; that you may not think that there is one thing in the Law, another in the Prophets, another in the Gospel. All Scripture teaches you nothing else, but restraint from the love of the world, that your love may speed on to God.
As a figure that the Law teaches this, Moses fasted forty days. As a figure that the Prophets teach it, Elias fasted forty days. As a figure that the Gospel teaches it, the Lord fasted forty days. And therefore in the mount too these three appeared, the Lord in the middle, Moses and Elias at the sides. Wherefore? Because the Gospel itself receives testimony from the Law and the Prophets. But why in the number forty is the perfection of righteousness? In the Psalter it is said, “O God, I will sing a new song unto You, upon a psaltery of ten strings will I sing praises unto You.” Which signifies the ten precepts of the Law, which the Lord came not to destroy, but to fulfil.
And the Law itself throughout the whole world, it is evident, has four quarters, the East, and West, South, and North, as the Scripture says. And hence the vessel which bare all the emblematic animals, which was exhibited to Peter, when he was told, “Kill and eat,” that it might be shown that the Gentiles should believe and enter into the body of the Church, just as what we eat enters into our body, and which was let down from heaven by four corners (these are the four quarters of the world), showed that the whole world should believe.
Therefore in the number forty is restraint from the world. This is the fulfilling of the Law: now the fulfilling of the Law is charity. And therefore before the Pasch we fast forty days. For this time before the Pasch is the sign of this our toilsome life, wherein, in toils, and cares, and continence, we fulfil the Law. But afterwards we celebrate the Pasch, that is, the days of the Lord's resurrection signifying our own resurrection. Therefore fifty days are celebrated; because the reward of the denarius is added to the forty, and it becomes fifty.
Why is the reward a denarius? Have ye not read, how that they who were hired into the vineyard, whether at the first, or sixth, or the last hour, could only receive the denarius? When to our righteousness shall be added its reward, we shall be in the number fifty. Yea, and then shall we have none other occupation, save to praise God. And therefore throughout those days we say, “Hallelujah.” For Halleluiah is the praise of God. In this frail estate of mortality, in this fortieth number here, as though before the resurrection, let us groan in prayers, that we may sing praises then. Now is the time of longing, then will be the time of embracing and enjoying. Let us not faint in the time of forty, that we may joy in the time of fifty.
Source: Sermons on Selected Lessons of the New Testament (New Advent)