The philosophical idea that human existence comes before any predefined nature or purpose was famously articulated by Jean-Paul Sartre, a prominent 20th-century existentialist. He introduced this concept in works like "Being and Nothingness" (1943) and elaborated on it in his 1945 lecture "Existentialism Is a Humanism." Sartre's assertion directly challenged traditional philosophical and theological views, which often posited that things, including humans, have an inherent essence or blueprint given by a creator or a universal order, before they come into being. As an atheist, Sartre rejected the notion of a divine plan or a fixed human nature, arguing instead that we are "thrown" into existence without any pre-established identity or objective.

The deeper meaning of this idea is profoundly liberating yet daunting. It suggests that unlike a manufactured object, which is created with a specific purpose (its essence preceding its existence), human beings first simply exist. It is through our conscious choices, actions, and experiences that we then create our own values, define our character, and give meaning to our lives. We are not bound by a predetermined path but are constantly in the process of becoming, perpetually shaping our own "essence". This radical freedom, however, comes with an equally radical responsibility, as we are solely accountable for who we become.

This philosophical stance has significant real-world applications. It encourages individuals to live authentically, resisting the temptation to conform to societal expectations or passively accept roles others impose upon them, which Sartre termed "bad faith". Whether in career paths, personal relationships, or the values we uphold, every decision, big or small, contributes to the ongoing construction of our self. It empowers us to actively take control of our lives and forge our own unique paths, finding meaning not in some external decree, but in the very act of self-creation. Even in the face of immense adversity, as Viktor Frankl's experiences demonstrated, the freedom to choose our response and define ourselves remains.