Life is a self-replicating algorithm in search for the philosophical concept of the best.
Say you need to create the best creature. First you need to quantify that. If you knew what purpose it should serve and what environment it would exist in, you could come up with a list of characteristics that it needs to possess. The only way to find the quantifiable best of something is to produce and compare all possible variations of that which you're looking for. So, you'd make every possible variation of the creature with all its required characteristics, then test and compare them in your particular environment and in the end you'll find the absolute best.
Now imagine you have to do the same, but you don't know any of the answers. What is it for? What environment it goes in? What characteristics does it need? Life is a way to search through all possible characteristics in all possible environments and for all possible purposes.
