Like other descriptions of time in the Word, "a day" or a number of "days" describe a spiritual state rather than our natural concept of time. A spiritual "day" describes a state of mind or a state in our relationship with the Lord rather than a 12-hour or 24-hour span of natural time. "Day" describes a state in which we are turned toward the Lord, and are receiving light (which is truth) and heat (which is a desire for good) from the Lord.

197. With the most ancient people, who were celestial, a serpent meant being completely watchful, and so also meant their sensory perception by means of which they were to show vigilance to avoid being harmed by the evil. This is clear from the Lord's words to His disciples,

Behold, I send you out as sheep in the midst of wolves; so be shrewd as serpents and simple as doves. Matthew 10:16.

And also 'the bronze serpent' which was raised up in the wilderness and which meant the Lord's Sensory Perception. He alone is Celestial Man, and He alone is completely watchful and provides for everybody. Whoever beheld it therefore was delivered.