上句见：Day396
The Story of Philosophy《哲学的故事》第1章Plato第7节VI. The Psychological Solution第11段第7句：

Those who pass this first test will receive ten more years of education and training, in body and mind and character. And then they will face a second test, far severer than the first. Those who fail will become the auxiliaries, or executive aides and military officers of the state. Now it is just in these great eliminations that we shall need every resource of persuasion to get the eliminated to accept their fate with urbanity and peace. For what is to prevent that great unselected majority, in the first test, and that lesser but more vigorous and capable second group of Eliminees, from shouldering arms and smashing this Utopia of ours into a mouldering reminiscence? What is to prevent them from establishing there and then a world in which again mere number or mere force will rule, and the sickly comedy of a sham democracy will reënact itself da capo ad nauseam? Then religion and faith will be our only salvation: we shall tell these young people that the divisions into which they have fallen are God-decreed and irrevocable — not all their tears shall wipe out one word of it. We shall tell them the myth of the metals:
"Citizens, you are bothers, yet God has framed you differently. Some of you have the power of command; and these he has made of gold, wherefore they have the greatest honor; other of silver, to be auxiliaries; others again, who are to be husbandmen and craftsmen, he has made of brass and iron; and the species will generally be preserved in the children. But as you are of the same original family, a golden parent will sometimes have a silver son, or a silver parent a golden son. Are God proclaims … that if the son of a golden or a silver parent has an admixture of brass or iron, then nature requires a transposition of ranks; and the eye of the ruler must not be pitiful towards his child because he has to descend in the scale to become a husbandman or an artisan, just as there may be other sprung from the artisan class who are raised to honor, and become guardians and auxiliaries. For an oracle says that when a man of brass or iron guards the state, it will be destroyed"(415).
Perhaps with this "royal fable" we shall secure a fairly general consent to the furtherance of our plan.
浙江大学译本：宗教和信仰是我们唯一的救赎：我们将告诉这些年轻人，他们此刻所得的是上帝的旨意，是不可违背的——流干眼泪也无济于事。

解析

1、Then religion and faith will be our only salvation:
宗教和信仰是我们唯一的救赎：
salvation: something that saves people or something from danger or difficult situation 解救；拯救
Vrba‘s extraordinary memory was his curse and a salvation.弗尔巴非凡的记忆力是对他的诅咒，也是他的救星。《经济学人》
2、we shall tell these young people that the divisions into which they have fallen are God-decreed and irrevocable
我们将告诉这些年轻人，他们所属的分层是上帝的旨意，不可改变的。
irrevocable: not capable of being changed; impossible to revoke不可改变的；不可推翻的
It's an irrevocable vow that I want to take.这是我想许下的不可改变的誓言。《道林·格雷的画像》
3、not all their tears shall wipe out one word of it.
即使流干眼泪也无法抹去其中的一个字。

这句讲出解决方案。

宗教和信仰是我们唯一的救赎：我们将告诉这些年轻人，他们所属的分层是上帝的旨意，不可改变的——即使流干眼泪也无法抹去其中的一个字。