4052. Furthermore such is the correspondence of the brain with the Grand Man that those whose first intentions are directed to what is good correlate with those parts in the brain which are the first beginnings there and are called the glands or cortical substances. But those whose first intentions are directed to what is true correlate with those parts in the brains which emanate from those first beginnings and are called fibres. But the following distinction has to be made - those who correspond to the right side of the brain are those with whom the will for what is good and so for what is true predominates, whereas those who correspond to the left side of the brain are those with whom the understanding of what is good and true and so the affection for such predominates. The reason for this is that the good done by those in heaven who are on the Lord's right springs from the will, but the good done by those on the Lord's left springs from the understanding. The former are the ones who are called celestial, but the latter the ones who are called spiritual.