At some places the thinking process is introduced before the actual creation starts. The verb used aik ata is very significant. One can guess that the Lord might have drawn a picture of the whole world before his mind, and then the creation might have started. Perhaps this may be cosmic creation which ultimately turns into the visible world. It means from that Highest Soul the space is produced.
Space creates wind, which means some sort of movement starts.
Then the heat which naturally comes out of any sort of action. The water indicates sort of flow, and ultimately the result is earth as a gross element. By keeping in mind the Upanisadic device of describing a thing from a subtle point of view to gross, this passage is interpreted in this manner. Though it is a fact that the whole world is created by the Supreme Being, still, it does not come out at once, but has a certain sequence. This is Upani ad's scientific method.