When did your existence begin? What are you? A thing? I am of the mind that it is more accurate to describe a human being as a process which begins with conception and ends with death. But when did you come into the picture? Were you always there, somehow asleep before slowly waking up to find yourself alive in this world as a creature of body and mind? In order to not confront such issues, most people prefer to keep busy with various activities - and if that doesn't do the trick, with more heavy distractions such as drugs and religious hysteria. But at the end of the day, when you're alone and silent, the doubt and the fear comes creeping back. Who are you, really? What is going on out there? 

You can say that trees have open intestinal functions. They send their roots down into the soil where they extract nutritients from whatever composted carcasses of formerly living beings through micro-electric discharges. You can also say that trees can see, insofar that they are light sensitive and able to turn their leaves in whichever direction that will provide the most sunlight. In many ways they are very much like us. Their strategies for survival are however very different in some key elements: Where trees have roots that search into the ground for the necessary nutritients, we have an intestinal tunnel through which we transport various composites of formerly living beings, extracting the necessary nutritients and discarding the rest through defecation. Where trees have light sensitive organs in their leaves, we have an entire surface which can detect changes in air density and charge - that which we call "temperature" - and also some specialised organs (our eyes) which will pick up a small portion of the spectre of electromagnetic currents that are reflected from surfaces in our surroundings and processed in our brains to create an image of the world, which we base our decisions to take whatever appropriate action in, based in an overall species-relative strategy for passing on our genetic material. 

You can say that all structured organisms living on earth are clusters of one celled organisms that are cooperating to create a complex form, or a creature. They are doing this because the genetic material in the cells are commanding them to do so. It isn't a matter of choice. An e-coli bacteria is an e-coli bacteria because of the genetic command. The same can be said about a gnat, a leopard, or a human monkey. The much famed "free will" that we boast is limited by a world of commands and necessities that leaves precious little room for choice. In the theatre of life, you play the part that's being handed to you. Your only option is to play it well, with passion and abandon, or to play it with the timid self importance of an actor who care more about what the audience will think than about doing justice to the play.