Heaven as his loyalty to life will permit. He recognizes that heavens truth is a delicious temptation of freedom but life is too valuable for him to give up. and earth's truth, and what choice to make .Another way of putting this is that earth's truth is nature with its fire, wind, rain, etc... Heaven's truth can be defined through many eyes as spiritual, imagination, or insight. So the enigmatic truth lies in all of us and around us. This is the heaven's truth that "Birches" describes after earth's truth. Eventually a universal truth lies at the end of the trip or possibly a truth that can satisfy our mind. Here the decision is made that he shall take both paths:

I'd like to go by climbing a birch tree

And climb black branches up a snow-white bank

Toward heaven, till the tree could bear no more,

But dipped its top and set me down again.

That would be good both going and coming back.

One could do worse than be a swinger of birches.(Frost 1109)

The summary of his choice is to pick both paths are written in these few words. Frost wants to climb a birch tree and go toward heaven until death prevents him from going any farther and then coming back down.

In conclusion, Frost does pick both paths of truths, heaven's truth and earth's truth. When he tried to find the divine truth he loved life too much for a one way path to heaven. So he decides to be a "swinger of birches," and find this divine truth as his love of both. A decision is made in which he is sure of winning. Frost swings between the truths but never makes himself accept one.