That is my short summary reflection on Saint Bernard of Clairvaux's incisive 5th Sermon On the Advent of the Lord: On the Middle Advent and the Triple Innovation. Below is my translation.
Saint Bernard says that Advent is making Christ take over your heart and your entire being. It's not enough to have Christ in your head or even in good works but first of all in the heart, forming all your affections, habits and your entire manner of being. Advent is having Christ within you really, always reshaping you from the old man to the new man! Advent is every day, every moment and it is the same as Christmas: Christ in the world between His first and last coming: the middle Advent: the now. It must be Christ's at least in you. "Keep Christ in Christmas!" indeed! especially on your heart!
ON THE ADVENT OF THE LORD: SERMON V
On the Middle Advent and the Triple Innovation
1. We were just saying to those who covered their wings with silver with the imitation of the virtues of Christ, sleeping in the midst of dangers, signifying two advents (the first and the last), but we did not say where they should be sleeping. There is a third advent in the middle between those (two advents) and in which those who know Him sleep delightfully: the other two (advents) are manifest, but this (middle) one is not. In the first the Lord was seen on the earth and related to men; as He Himself testifies: "They saw Him and hated Him" (Jn. 15:24); in the last, "all flesh shall see the salvation of our God (Lk. 3:6); and "they shall look on the One they transfixed" (Jn. 19:37). The middle one is hidden, in which only the elect see Him in themselves and their souls are saved. In the first He came in the flesh and in weakness (infirmitate); in this middle one, in spirit and virtue; in the last one, in glory and majestyl For through virtue glory is achieved; since "the Lord of virtues Himself is the King of glory (Ps. 23:10). And in another place the same prophet says: "that I may see your virtue and your glory" (Ps. 62:3). Thus this middle advent is a type of path, by which from the first the last is attained. In the first Christ was our redemption; in the last He shall appear as our life; in this one He is our rest and consolation that we might sleep in the midst of dangers.
2. But so that these things we say about this middle advent might not appear invented, listen to the Lord Himself. "If anyone loves Me," He says, "he will keep My words (sermones) and My Father will love him and We will come to him (Jn. 14:23). But what does it mean "If anyone loves Me, he will keep my words?" For I have read in another place "He who fears God will do good works (bona) (Ecclesiasticus 15:1). But, I sense that something more than this applies to the one who loves God, when it says that he will keep his words. For where are they to be kept (servandi)? In the heart, no doubt! as the prophet says: "I hid your words in my heart to not sin before you." (Ps. 18:11) And how are they to be kept in the heart? Would it be enough to keep them in the memory? To the one who would keep them in this way the Apostle would say that "knowledge puffs up." (I Cor. 8:1) And, in the end, the memory easily forgets too. You can best keep the word of God the same way that you best keep food for the body, for it also is living bread and nourishment for the soul. Earthly bread, while in the breadbox can be stolen by a thief, eaten by mice or spoil with time. But when you shall have eaten it do you fear any of this? Keep the Word of God in this way, because "blessed are they that keep it. (Lk. 11:28) Make it go to the entrails of your soul. Make it go to your very customs and affections. Eat what is good and you will delight in the fatness of your soul. Do not forget to eat your bread, lest your heart dry up. Rather, fill your soul with fat and substance.
3. If you keep the word of God thus, He will no doubt keep you, for the Son will come to you with the Father, the great Prophet will come Who will renew Jerusalem and He will make all things new. This coming will make it such that just as we carried the image of the earthly man, we shall also carry the image of the heavenly man (I Cor. 15:49); it make it such that just as the old Adam was spread throughout the whole man and occupied the whole, so now Christ possesses him totally, Who created him totally, redeemed him totally and will glorify him totally; just as He is that Lord Whom made the total man entirely saved on the Sabbath. At one time the old man was in us, that liar was in us, so in our hands as in our mouth as in our heart. In the hands in two ways: by evil deeds and shameful acts. In the mouth likewise by arrogance and detraction. In the heart by the desires of the flesh and the love of temporal glory. But if man is now made a new creature in Him, the old things pass away, and against the hands' evil deeds: innocence; against shameful acts: continence; against arrogance in the mouth: the word of confession; against detraction the edifying word, that the old things should leave our mouth. In the heart, against carnal desire: chastity; against temporal glory: humility. And see if it is not so that each of the elect receives Christ, the Word of God in these three things (hands, mouth and heart), when it is said to them: "Put me like a seal upon your arm, like a seal upon your heart; (Cant. 8:6) and in another place: "The word is close to you in your mouth and in your heart." (Rom. 10:8)