There are great truths and small ones.
First of them belongs to the scientific views of nature. They are great for their power to cover large domains of knowledge and life.
The small truths are so because of their limited scope. Most of them belong to those particular experiences of life which are characterized as having a moral meaning. Thus, it is true that goodness improves the human behavior, but it is a truth that occurs only in the limited area of the individual life.
For it occupies only a limited space of reality, the small truths are claimed by many as if they would be greater.
Their imaginary greatness cannot be reached by extending their scope, but by mixing them with alien matters. When someone claims that the word as such is subdued to a moral order, he cannot really make the small moral truths greater, but allows to the idea of a universal order to conjoin them.
The mixing of small truths with alien ideas takes place only through language. Therefore, someone can preserve the purity of small truths only by refusing to discuss about them and by assuming them in his life. But when someone denies or do not know the great truths, the living of small truths will have to fight with the persistent feeling of smallness. Thus, the people with a humble moral life are always tempted to ground their life on the mixed truths.
Meanwhile, the defender of great truths finds himself in the position of someone who must come out from the limited scope of his life. And he does so by the use of language, too. However, since he is acquainted with those truths which are not mixed with other ideas for being great, any return to the small truths should prevent him to not search for supporting them through alien ideas, not even through those great truths.
In other words, the great scientific truths cannot teach us how to morally live, but can teach us to live morally without any useless appeal to alien ideas.