While most philosophers of the day were very serious about their work, Schopenhauer, known as the "philosopher of pessimism," made it quite plain that he regarded the world and our lives in it as a bad joke. For him, the nature of reality was itself, horrific.
In his masterpiece The World as Will and Representation, Schopenhauer put forth that the world, as we experience it through our senses, consists of representation or mere phenomena as was depicted by Kant. That which supports this representation, however, is not the ultimate reality of things-in-themselves (noumena), which according to Kant are unknowable, but the entire phenomenal façade of the world. What we experience, according to Schopenhauer, is supported by a universal Will.
The world, in effect, has two aspects, an outer aspect revealed to our senses, and an inner aspect - the world as Will. For Schopenhauer, Will replaces the Kantian noumenal and unknowable world of a thing-in-itself. Likewise, our sensory experience of the world is not our only access to it. Schopenhauer argues that 'a way from within stands open to us to the real inner nature of things.' We have perceptual experience of ourselves as bodies located in a world of objects in space and time, but we also have direct experience of ourselves as will. The phenomenal world is the appearance of Will and the noumenal world is nothing but a world of Will. Therefore, our own inner experience of willing is key to understanding the Kantian thing-in-itself.
Unfortunately, it is this Will that brings about all the misery and suffering in the world and ultimately only leads to death. It blindly manifests itself as a constant desire and ceaseless striving for existence. In fact, says Schopenhauer, human life is driven by nothing but constant cravings and appetites of lust and ambition which, when satisfied, quickly turn to boredom, only to reawaken in other useless cycles.There is, however, a way out from the tyranny of the will and its trappings of egoism, and that is self-denial and the saintly renunciation of life. Once one realizes the futility of all life and the blind cravings of a single, cosmic Will, one can renounce all gratification and deny the will. Only then can one can reach a state, such as the Buddhists aspire to, Nirvana.
While Schopenhauer advocated self-denial and a stoic type of existence, he himself lived in bourgeois comfort denying himself very little. He ate well, dressed well and enjoyed the company of various women.