Arcana Coelestia # 3137
3137. 'At the spring' means the enlightenment of them from Divine truth. This is clear from the meaning of 'a spring' as truth, dealt with in 2702, 3096, here Divine truth, as above in 3131. Because the Word is Divine truth it is therefore called 'a spring'. That 'standing at the spring' here embodies in the internal sense the enlightenment of things in the natural man follows from the train of thought; for where Divine truth is, enlightenment is there.
Foot
The foot, as in Deuteronomy 33:3, signifies an inferior principle. To set the right foot on the sea and the left on the earth, as in Revelation 10:2, signifies that the Lord has the universal church under His intuition and dominion.
(Odkazy: Apocalypse Explained 10 [2]; Arcana Coelestia 2714)