Classical philosophy maintained that the final state of being of a thing existed before the thing itself. In other words, an acorn can't exist unless the idea of an oak tree already exists. To say that existence precedes essence is to say that a thing exists first, independent of any final goal or purpose. This, then concludes that there is no such being as God. To say that essence precedes existence is to say that the idea of a thing comes before the thing itself. In other words that God created the world (he had the idea to create a new thing, before actually doing it). Tabula Rasa is the thesis that individuals are born without built-in mental content and that their knowledge comes from experience and perception. Within this thinking you can assume that existence precedes essence because without existence, there would be no way to form experience or perception. I think it depends on how exactly you are defining essence. If you use it interchangeably with purpose or meaning, then I think the only way essence could precede existence is if God created us. Purpose has to be given, with intention, as we humans do with the things we create. The purpose of a drawer is to hold our stuff, because that is the purpose we have given it, not because the purpose exists inherently in the drawer(drawer does not have a brain). The only way human beings could have purpose is if God has assigned us purpose. Otherwise our lives are initially meaningless, until we give meaning to them personally(through God). If you use 'essence' to describe the properties of a human being (instincts/ emotions), then surely essense and existence begin pretty simultaneously. Essence may even come first, since it seems like we start developing properties before we become a real person (before we are aware of ourselves).