"We have already seen in nature-without-knowledge her inner being as a constant striving without aim and without rest, and this stands out much more distinctly when we consider the animal or man. Willing and striving are its whole essence, and can be fully compared to an unquenchable thirst. The basis of all willing, however, is need, lack, and hence pain, and by its very nature and origin it is therefore destined to pain. If, on the other hand, it lacks objects of willing, because it is at once deprived of them again by too easy a satisfaction, a fearful emptiness and boredom come over it; in other words, its being and its existence itself become an intolerable burden for it. Hence its life swings like a pendulum to and fro between pain and boredom, and these two are in fact its ultimate constituents. This has been expressed very quaintly by saying that, after man had placed all pains and torments in hell, there was nothing left for heaven but boredom."