5 ideas
Human fortune divides into three categories: what a person is (health, temperament, intellect, character), what a person has (property and possessions), and what a person represents in others' eyes (rank, honor, fame). Only the first travels with you everywhere and cannot be taken away by others. Yet people spend most of their effort on the second and third, which bring comparatively little happiness.
When we read, another person does our thinking for us, and we merely repeat their mental process. Constant reading without pauses for reflection weakens the capacity for original thought, much as a spring loses its tension when a weight always rests on it. Only knowledge that has been independently thought through becomes truly one's own. Unexamined reading merely piles up borrowed material.
In "On Noise" Schopenhauer singles out the cracking of whips by carters in narrow town streets as the most inexcusable noise, because it shatters a thinker's train of thought for no useful purpose. He proposed that drivers be punished for it. He treats a person's tolerance of noise as evidence of how little they are thinking, since a mind with no thoughts has nothing to interrupt.
A group of porcupines crowd together on a cold day for warmth, but their quills prick one another, so they draw apart. Cold drives them back together, and they shuttle back and forth until they settle at a moderate distance. At that distance they tolerate each other. Society works the same way: loneliness pushes people together, their disagreeable qualities repel them, and politeness is the resulting compromise of keeping a tolerable distance.
Pain and want are positive: they are directly felt and demand attention. Satisfaction and happiness are negative: they register only as the removal of a pain or need. We notice health, youth, and freedom only once they are gone. The prudent aim of life is therefore to avoid suffering, not to chase pleasure.