'Highest' denotes the 'inmost,' because interior things, with person who is in space, appear as higher things, and exterior things as lower. But when the idea of space is put off, as is the case in heaven and in the interior thought of a person, then the idea is put off of what is high and deep, for height and depth come from the idea of space. In the interior heaven, the idea of 'interior and exterior' things is different, because this idea adheres to a somewhat spatial nature. But there is the idea of more perfect or imperfect state, for interior things are in a more perfect state than exterior things because interior things are nearer to what is divine, and exterior things are more remote. This is the reason why what is highest signifies what is inmost.

(References: Divine Love and Wisdom 103)