Existence, I think can bed quantified. It is a thing, tangible or intangible, which has an effect on environment.

@DPMartin
I agree with you in that hate 'has it's place'. The difficulty there is where is it's place, and where isn't? Who decides what is "okay" or "good" to hate, and what isn't? Society? The law? Do you even think there should be a universal guideline of what is okay to hate? Does it differ from person to person? If so, is this the root of what we believe to be evil? -by this, I mean if one person doesnt hate somethjng (e.g. peadophillia) they may go on to commit it, and then this is, undeniably, evil.

There are a lot of questions here I know, but I would love to see your perspective on this topic, thanks.

From a biological perspective I think it's very easy to qualify the meaning of life: species survival. For the brain of us complex beings however, this isn't enough and we need stimulation, stimulation which causes happiness. I believe that happiness is our driving force and, I know it sounds corny but what is a life without happiness. But what makes us happy? This is the part which differs between individuals. Fulfilment, satisfaction, relaxation? Never once have I read anything which can quantify everything which may make a person happy, but simply, whatever makes a person happy should be the meaning of their life (as long as they aren't harming others).