Feelings of pain or pleasure or some quality in between are the bedrock of our minds. We often fail to notice this simple reality because the mental images of the objects and events that surround us, along with the images of the words and sentences that describe them, use up so much of our overburdened attention. But there they are, feelings of myriad emotions and related states, the continuous musical line of our minds, the unstoppable humming of the most universal of melodies that only dies down when we go to sleep, a humming that turns into all-out singing when we are occupied by joy, or a mournful requiem when sorrow takes over.

— Antonio Damasio, Looking for Spinoza