He urges him to leave his studies and enter religion, and sets before him the miserable end of Thomas of Beverley.
To his dearly beloved son, Thomas, Brother Bernard, called Abbot of Clairvaux, that he may walk in the fear of the Lord.
1. You do well in acknowledging the debt of your promise, and in not denying your guilt in deferring its performance. But I beg you not to think simply of what you promised, but to whom you promised it. For I do not claim for myself any part of that promise which you made, in my presence, indeed, but not to me. Do not fear that I am going to reprove you on account of that deceptive delay: for I was summoned as the witness, not as the lord of your vow.  I saw it and rejoiced; and my prayer is that my joy may be full -- which it will not be until your promise is fulfilled. You have fixed a time which you ought not to have transgressed. You have transgressed it. What is that to me? To your own lord you shall stand or fall. I have determined, because the danger is so imminent, to deal with you neither by reproofs nor threats, but only by advice -- and that only so far as you take it kindly. If you shall hear me, well. If not, I judge no man; there is One who seeketh and judgeth; for He who judgeth us is the Lord (1 Cor. iv.4). And I think for this cause you ought to fear and grieve the more, inasmuch as you have not lied unto men, but unto God. And though, as you wish, I spare your shame before men, is that shamelessness to go unpunished before God? For what reason, pray, is there in feeling shame before the judgment of man and not fearing the face of God? For the face of the Lord is against them that do evil (Ps. xxxiv.16). Do you, then, fear reproaches more than torments; and do you, who tremble at the tongue of flesh, despise the sword which devours the flesh? Are these the fine moral principles with which, as you write, you are being stored in the acquisition of knowledge, the ardour and love for which so heats and excites you that you do not fear to slight your sacred vow?
2. But, I pray you, what proof of virtue is it, what instance of self-control, what advance in knowledge, or artistic skill, to tremble with fear where no fear is needful, and to lay aside even the fear of the Lord. How much more wholesome the knowledge of Jesus and Him crucified -- a knowledge, of course, not easy to acquire except for Him who is crucified to the world. You are mistaken, my son, quite mistaken, if you think that you can learn in the school of the teachers of this world that knowledge which only the disciples of Christ, that is, such as despise the world, attain; and that by the gift of God. This knowledge is taught, not by the reading of books, but by grace; not by the letter, but by the spirit; not by learning, but by the practice of the commandments of God: Sow, says the Prophet, to yourselves in righteousness, reap the hope of life, kindle for yourselves the light of knowledge (cf. Hos. x.12). You see that the light of knowledge cannot be duly attained, except the seed of righteousness [first] enter the soul, so that from it may grow the grain of life, and not the mere husk of vainglory. What then? You have not yet sown to yourself in righteousness, and therefore you have not yet reaped the sheaves of hope; and do you pretend that you are acquiring the true knowledge? Perchance for the true there is being substituted that which puffeth up. You err foolishly, Spending thy money for that which is not bread, and thy labour for that which satisfieth not (Is. lv.2). I entreat you, return to the former wish of your heart, and realize that this year of delay which you have allowed to yourself has been a wrong to God; is not a year pleasing to the Lord, but a seedplot of discord, an incentive to wrath, a food of apostasy, such as must quench the Spirit, shut off grace, and produce that lukewarmness which is wont to provoke God to spue men out of His mouth (cf. Rev. iii.16).
3. Alas! I think that, as you are called by the same name, so you walk in the same spirit as that other Thomas, once, I mean, Provost of Beverley. For after devoting himself, like you, to our Order and House with all his heart, he began to beg for delay, and then by degrees to grow cold, until he openly ended by being a Secular, an apostate, and, twofold more, a child of hell, and was cut off prematurely by a sudden and terrible death (S. Matt. xxiii.15) -- a fate which, if it may be, let the pitiful and clement Lord avert. The letter  which I wrote to him in vain still survives. I simply freed my own mind, by warning him, so far as I could, how it must soon end. How happy would he have been if he had taken my advice! He cloked his sin. I am clean from his blood. But that is not enough for me. For though in so acting I am quite at ease on my own account, yet that charity which seeketh not her own (1 Cor. xiii.5) urges me to mourn for him who died not in safety, because he lived so carelessly. Oh! the great depth of the judgments of God! Oh! my God, terrible in Thy counsels over the sons of men! He bestowed the Spirit, whom he was soon again to withdraw, so that a man sinned a sin beyond measure, and grace found entrance that sin might abound; though this was the fault, not of the Giver, but of him who added the transgression. For it was the act of the man's own freewill (whereby, using badly his freedom, he had the power to grieve the free Spirit) to despise the grace instead of bringing to good effect the inspiration of God, so as to be able to say: His grace which was bestowed on me was not in vain (1 Cor. xv.10).
4. If you are wise, you will let his folly profit you as a warning; you will wash your hands in the blood of the sinner, and take care to release yourself at once from the snare of perdition, and me from horrible fear on your account. For, I confess, I feel your erring steps as the rending of my heart, because you have become very dear to me, and I feel a father's affection for you. Therefore, at every remembrance of you that sword of fear pierces through my heart the more sharply, as I consider that you have too little fear and uneasiness. I know where I have read of such: For when they shall say peace and safety, then sudden destruction cometh upon them, as travail upon a woman with child, and they shall not escape (1 Thess. v.3). Yea, I foresee that many fearful consequences threaten you if you still delay to be wise. For I have had much experience; and Oh! that you would share and profit by it. So believe one who has had experience; believe one who loves you. For if you know for the one reason that I am not deceived, for the other you know also that I am not capable of deceiving you.
 Bernard regards as a vow that kind of promise by which a man had determined in his presence to enter the religious state. See Letter 395 and Sermons on Canticles, 63, n. 6, in which he mourns the lapse and fall of novices.  No. 107.
 No. 107.