The letter E, as pronounced in 'they', represents a sound of the spiritual heavens; and in Hebrew, words with this vowel partake of the spiritual class, or refer to truth. No letter in the Hebrew alphabet represents it, but a diacritic symbol is employed. The Greek letter is Epsilon (E, e) or Eta (H, n). (Heaven and Hell 241, Doctrine Regarding Sacred Scripture 90[2], Spiritual Experiences 5112; De Verbo 4[2])

(References: Arcana Coelestia 2403, Genesis 14, 19, 19:14)

In Exodus 15:8, this signifies falsities gathered together. Waters normally signify truths, but in this case, where they were blocking the escape of the Children of Israel from slavery and signify the opposite: falsities.

(References: Arcana Coelestia 8286)