The snake symbolizes something unconscious; it is the instinctive movement or tendency; it shows the way to the hidden treasure, or it guards the treasure. The snake has a fascinating appeal, a peculiar attraction through fear. Some people are fascinated by this fear. Things that are awe-inspiring and dangerous have an extraordinary attraction. The serpent shows the way to hidden things which leads man to go beyond the point of safety, and beyond the limits of consciousness.
1925 Seminar
Carl Jung
Edit after Eugène Leroux and Alexandre-Gabriel Decamps (Drie heksen uit Shakespeares Macbeth) (Rijksmuseum) (Ed. Lic.: CC BY-NC 3.0)
Night is not less wonderful than the day . . . it is lit by the splendor of the stars and it reveals things to us that the day does not know. Night is closer than day to the mystery of all beginning. The abyss is open only by night: day spreads a veil over it.
Nicolas Berdyaev, "The Middle Ages"