"I have no pity! I have no pity! The more worms writhe, the more I yearn to crush out their entrails!" signifies a ruthless, almost catabolic attitude towards suffering and cruelty. The speaker expresses a desire to inflict pain and shows an enjoyment or satisfaction in causing hurt, emphasizing a lack of compassion.

"It is a moral teething, and I grind with greater energy, in proportion to the increase of pain," suggests that experiencing suffering or cruelty acts as a kind of painful process of growth or development for the speaker. The analogy compares this to teething, implying that pain fosters strength or maturity, even if it is harsh or destructive.