In my Christian Heritage class today we discussed the first four ecumenical councils. The discussion of these councils inevitably leads to the Christian doctrine of the Trinity.
Every year, before I launch into the lecture, I try to get the class to explain the Trinity from their conception. What always becomes clear is that any positive attempt to describe the Trinity always leads to some heresy or another. Take all of the modern examples and analogies and they fall into one of a number of forms of heresy.
The egg is an interesting analogy: one egg, but divided into three parts, shell, yolk, white. Yet, these substances can be separated whereas the Trinity cannot. Once I separate the parts, I am not seeing the entire egg, only a part. In the orthodox formulation of the trinity, when one views one person of the trinity, they view the entire godhead. Hence, the egg analogy does not hold up.
Thus, when one speaks of the Trinity, formulations must be negative, saying what it is not, not what it is. Hence, when talking about the nature of Christ, Chalcedon could only construct its formula in negative terms, i.e., the Son is two natures, without confusion, without change, without division, without separation (ἀσυγχύτως, ἀτρέπτως, ἀδιαιρέτως, ἀχωρίστως).
The Trinity, and the dual nature of Christ are mysteries. They are mysteries not to be solved, but to be wondered at. Not to be figured out, or brought under our control, but rather to be marveled at. It is in the mysteries of Christianity, in the places where we cannot conform the reality of God to the finiteness of our mind, where we truly have the opportunity to worship, to stand in awe at a God who is so profoundly beyond our understanding, to rest in the fact that we are not in control.