"Thinking hurts" — this is how the German philosopher Georg Simmel is said to have consoled his students. The Jewish philosopher Martin Buber (1878-1965) would give this ironic remark of his teacher an ethical twist by noting that "thinking" can also hurt others.

For in our encounter with our fellow human beings we often tend to allow established categories of thought to determine how we relate and perceive them. In doing so, Buber held, they in effect become objects of thought, an "It", rather than indivuals whose existential reality is impervious to the markers that thought constructs.