Existentialists believe that existence precedes essence. This premise not only applies how to humans define themselves, but also to the philosophy itself, which though believed a modern line of thought, found its foundation in the twenty-five hundred-year-old words of Heraclitus. Though only a small batch of aphoristic fragments remain of his work, the fragments on valuation from the ancient Ephesian philosopher influenced not only the Greek philosophers that followed him, but also the school of modern existentialism. Heraclitus logically explored a world of subjective values, a concept near to the core of existentialist philosophy, and his early humanist ideals echo in the works of many existentialists, especially 19th century German existentialist, Friedrich Nietzsche.
Like existentialism, Heraclitus is often misunderstood and mistaken for pessimistic by proclaiming a world without absolute authority. Heraclitus and existentialism provide a view of existence where the very value judgment that decries their pessimism comes from the subjectivity of critics lacking any guide or grounds for such thought. Key to understanding both Heraclitus and the views of existentialism, is the insistence that no objective values exist. Heraclitus incepts the sentiment of modern existentialist philosophers that God-given objective values do not exist and humans place worth without the aid of an absolute authority.
Heraclitus and Nietzsche both find admirable an individual who creates a personal set of values in favor of the subjective values of society, and does this with logic, reason, and society in mind. Nietzsche conceived of the "overman" to express this Heraclitian ideal of an individual that knowingly acts without the aid of societal values or God.