Thou hast set all the borders of the earth - Thou hast established all the boundaries of the world; that is, the boundaries of the earth itself; or the natural bonndaries of nations and people, made by seas, mountains, rivers, and deserts. The language in regard to the first of these - the earth itself - would be derived from the prevalent mode of speaking, as if the earth were a plane, and had limits - a common mode of expression in the Scriptures, as it is in all ancient writings, and in the common language of men, even of philosophers. In regard to the latter idea, the language would imply that God had fixed, by his own power and will, all the natural boundaries of nations, or that his dominion is over all the earth. There are natural boundaries, or arrangements in nature, which tend to break up the one great family of man into separate nations, and which seem to have been designed for that. Compare Acts 17:26. Over all these God presides, and he has his own great plans to accomplish by the arrangement.
Thou hast made summer and winter - literally, as in the margin, “Summer and winter, thou hast made them.” That is, he has so made the earth that these various seasons will occur. The fact that there are different seasons of the year, or that the year is divided into seasons, is to be traced to the agency of God. He has so made the world that these changes will take place. Nothing is the result of chance; all things in the arrangements of nature are by his design.