Who is this?

As this is published, I shall be at church celebrating the most profound moment in history (and one of the five most important so far - other candidates being the Creation, the Fall, the Crucifixion and the Resurrection).  What happened?  God became man.  What does that mean, and why did it matter?
Who is this Jesus, this "God the Son"?  In John 1 He is called called by the Greek term "logos", often translated "Word" (we shall consider another translation - and hence another meaning - shortly).  In Colossians 1 he is called the "image" of God.  In the Creed we say that Jesus is "eternally begotten of the Father" (i.e. of the Creator, the startpoint, the "I am" that simply is and had no beginning).
Through the past two thousand years, the Church has struggled to make sense of this.  The only positive account of this (i.e. an account that does not proceed by saying "it is not this way, and not that way" but, instead, says "it is something like this") that I am not aware of being condemned as heresy is the account offered by Melanchthon in Loci Communes (though I doubt it was original to Melanchthon).  Melanchthon describes the Son as "the image begotten by the deliberation of the Father", going on to say "He is called the Word because he is begotten by consideration.  He is called the image because the consideration is the image of the thing considered."
If this is a productive thought, then the Son is the Creator's self-conception, his self-awareness, and because God is perfect, His self-conception is a perfect image, sharing His essence.
But this is only the beginning.  For the term "Word" does not exhaust the meaning of the term "logos".  Logos was the term the philosopher Heraclitus used to describe that from which everything was made.  For Heraclitus the logos was the divine reason, the divine spark, the divine fire.  Everything in the world was in flux, undergoing change.  No thing, no material substance was constant.  Instead, what was invariant in the world was its principle of organisation.  We might be tempted to say that the logos were the laws of nature, but if those laws change (as perhaps they do) then Heraclitus' logos would be the principle according to which they change.
The Evangelist John says of his logos, his Word, clearly endorsing Heraclitus' position: "Through [the logos] all things were made; without Him nothing was made that has been made."
So, if we have it right, this logos, this Word is God's self-conception, the invariant principle in Creation, through which everything was made.  Clearly, we have before us a truly spectacular being.  But the most extraordinary thing is yet to come.  For John tells us "The [logos] became flesh and made his dwelling among us."
How amazing is that!  This spectacular being became human, living as one of us!  God's self-conception, that through which the entire universe was made, could become a man.
There was a purpose in the logos becoming a man, a great purpose, but let us focus on the wonder of the fact, rather the point, for a moment.  For it implies a quite extraordinary status for human beings.  Perhaps we knew this already - after all, in Genesis 1 we are taught that God made us in His own image.  But to recognise quite what this implies - that human beings are such that we can, in principle, encapsulate God's self-image, embody the organising principle of the Universe - is surely extraordinary.
In many ways, it is this part of the Christian story that most stretches one's credulity.  A world created to be good in essence, sin leading to death, people healed of infirmities, a man walking on water, people rising from the dead, sin conquered through an unjust death, salvation as a free gift for the faithful regardless of their wickedness, immortality - all these notions seem like they'd need pretty solid evidence to make one believe in them.  But, implausible as many of these ideas are, they are surely dwarfed in their bizarreness by the notion that the logos could become a man.
If that is right - if, if - then humanity is surely a remarkable thing.  And the sufferings and triumphs of humans take on a different status.  Certain secular thinkers believe that the key ethic in life concerns the promotion of pleasure and minimisation of pain, where pleasure and pain can be experienced by other creatures as well as humans.  Richard Dawkins considers a foetus to be human, but notes (which I suspect is true) that a foetus suffers less in an abortion than does a cow being slaughtered.  But a cow was not made in God's image, and the logos did not become a cow.
Perhaps, rather than focusing on how the Incarnation (the taking on of flesh) of the logos makes humans qualitatively superior to the other animals (for we are animals, created like the others), it might be more helpful to focus on how it should mould our thinking about humans in themselves.  When someone somewhere suffers or triumphs - regardless of how far she is from you, regardless of whether you have never seen her, regardless of whether she is related to you in some way or is in any sense useful to you - what suffers or triumphs is a being that could have been the logos made flesh.  Her suffering or triumph is, for that reason, one of the most important things in the entire universe - probably more important than obvious great events, such as hurricanes or asteroid strikes on Jupiter or supernovae or the swallowing of distant galaxies in black holes.  Knowing the Incarnation, we cannot continue to think tribally, to think that what really counts is the flourishing of ourselves and our families and friends.  Other humans cannot be things to use, obstacles we must overcome.  And no Christian society could insulate itself from the sufferings and triumphs of other societies, either.
The Incarnation thus tells us something remarkable about who we are, or at least who we could be.  If it really happened, it is not something humanity can ignore; it changes everything.