It can be hard to know where to begin with a philosopher. Over the years, I've come to see philosophy as kind of like building a house: it's best to begin with the foundation, rather than the roof.

Similarly, many philosophical projects can be traced back to some foundational "starting point" -- an assumption or an idea upon which the rest of the project is built. I believe that in Sartre's case, a good place to look for such a starting point is in the following phrase: "Existence precedes [comes before] essence", a phrase Sartre delivered during a lecture titled 'Existentialism is a Humanism'.

Sometimes called the 'motto' of existentialism, Jean-Paul Sartre's "existence precedes essence" was first introduced to unite two very different phases of existentialist thought (the Christian existentialists and the atheist existentialists). But I also think this phrase serves as an excellent entry point into Sartre's philosophical project.

This is because many of Sartre's most well known ideas and phrases -- 'bad Faith', "man is condemned to freedom", and so on -- are actually built upon this fundamental idea. But where did it come from, what does it mean, and how did it come to shape modern existentialist thought?

We'll take a look here at some of the history that went into the 'making' of this concept, and how Sartre's "existence precedes essence" sums up the point of departure between existentialism and other, previous lines of thought in philosophy.