Adam Clarke on Deuteronomy 10:14

Behold, the heaven and the heaven of heavens - All these words in the original are in the plural number: הן השמים ושמי השמים hen hashshamayim, ushemey hashshamayim; behold the heavens and the heavens of heavens. But what do they mean? To say that the first means the atmosphere, the second the planetary system, and the third the region of the blessed, is saying but very little in the way of explanation. The words were probably intended to point out the immensity of God's creation, in which we may readily conceive one system of heavenly bodies, and others beyond them, and others still in endless progression through the whole vortex of space, every star in the vast abyss of nature being a sun, with its peculiar and numerous attendant worlds! Thus there may be systems of systems in endless gradation up to the throne of God!