For Kierkegaard, truth is a subjective reality which we must live, not something to simply consider and discuss. His self-consciousness and self-examination highlight the practical demands of existence, and he opposes the speculative thinking of philosophical idealists. Kierkegaard says much of life's meaning depends not on external conditions, but on our internal choices about relating to them. He urges us to live with purpose and emphasizes that our task is not knowing but doing.
In Either/Or, he concentrates on sensual indulgence versus duty and the avant garde versus tradition. In Sickness unto Death, Kierkegaard diagnoses a spiritual disease throughout society: despair. Kierkegaard argues that we are estranged from the source of our very being as we try to escape the moral responsibility of the self.