Who/what are we? We are not our thoughts. Thought is nothing more than electrical impulses firing through our central nervous system and with time, can be silenced through meditation. We are not our emotions. Emotion is an electrochemical process that takes place as our body's reaction to thought; not as some people would like to believe, a reaction to external stimuli (10 people can watch the same event and emote 10 different responses). Our physical body is nothing more than a portable chemistry lab "issued" without a user's manual or warranty. What we commonly consider "ourself" is nothing more that a collection of ideas, desires and prejudices wrapped in a biological processing plant. It is taken for granted that "we" stop where the skin ends and the air starts. Is a comatose body the prison for a soul or did God just forget to turn off the utilities after the eviction notice was posted?
The "past" is an illusion that no longer exists, though evidence of past events sometimes remains. The future can be theorized upon (semi-accurately, too) but is ultimately nothing more than a concept brought about by common institution. All that exists is the present moment, something so fleeting as to be immeasurable (it’s gone by the time we think about it). But in each moment is that most precious of opportunities: existence. Existence is pure action.
Knowing that every action is, itself, a reaction to previous action, and will in turn engender further reaction in a never ending, interdependent and interrelated, all encompassing universe, we can begin to see ourselves in the world around us- and the world around us in ourselves. We are all one. Not in some cosmic, tripped out new age kind of way, but in a very concrete sense that is in the sustenance we take in, poop we flush, relationships we share with others and the mosquito we squashed that could have been a meal for the baby bird nested just outside our kitchen window. The examples are as infinite as the universe- because the universe is the example.
In a more rural tone: we can not see our own eye, bite our teeth nor pull ourselves up by our own boot straps. Asking of existence before or after existence is unanswerable. This is Joshu's "mu" in response to being asked if a dog has Buddha-nature. We must learn to ask appropriate questions to begin seeking usable answers.