 Look at the mechanics, fine. But the beginning of this regenerative process where tree begets tree begets tree begets tree so long as isn't diseased and dined along the way is something of a mystery in a tree, no less a multi-celled complex organism like you, me, or Max, the family pet even. Life is indeed a miracle and it is God who enacts life. And Isaiah is reminding us that that inaction of life is indeed something divine.