Praise In Summer

This poem reminded me of a sonnet, especially with the ABAB rhyme scheme. In a few things I read about the author, Richard Wilbur, it said his work was characterized as a formal and refined beauty which I agree with since this poem Praise In Summer is beautiful and flows well.
"Obscurely yet most surely called to praise, As sometimes summer calls us all, I said The hills are heavens full of branching ways". I found this poem to be very difficult to determine the meaning. I thought perhaps these first few lines is talking about that feeling you get when it's just a beautiful day and you want to go outside and enjoy it, it's like your called to go outside. The hills could be the different paths you can take on your journey outdoors.
"Where star-nosed moles fly overhead the dead; I said the trees are mines in air. I said See how the sparrow burrows in the sky!" I figured the mole part was literal, since they are burrowing animals they can literally move over the dead if they are burried in the ground. I did some research on star-nosed moles though and found they lived in marshes and wetlands, so the part that they fly overhead the dead was confusing because usually corpses are not burriend in wet ground. Such as in New Orleans, all graves are above ground because they don't want the graves to get swamped. The tree part could mean that the trees hold a lot of value such as a literal mine with precious stones inside does. The tree is of value to the sparrow so that is may rest in the tree, which is like burrowing in the sky.
"And then I wondered why this mad instead Perverts our praise to uncreations, why Such savor's in this wrenching things Awry. Does sense so stale that it must needs derange The world to know it? To a praiseful eyes Should it not be enough of fresh and strange That trees grow green, and moles can course in clay, And sparrows sweep the ceiling of our day?" I am really unsure as to what he means by this and why he italicized instead.