The words, in other words. And with them the intuition of the world, the way of shaping meaning, that the words embody. The world in Russian is not quite the same as the world in English, or in French, or in Chinese, or in Aeolic Greek. This is a difference less of culture than of sensibility, awareness, perception. One language perceives things that another doesn't.
Translation is an ever-failing attempt to get there.
The impulse is right, but losses are inevitable. No one English word can render it, and the translator is always forced to decide, sometimes arbitrarily, exactly which feeling the character is experiencing, thus limiting the meaning. It is an emotion defined as an act of tearing, a strained anguish, maybe heartache, if it weren't so overused in English. Naso, multus es et pathicus. Naso, mool'tis is it pathic, cuss.