'A shekel' signifies the price or estimation of good and truth, and 'half a shekel' signifies the determination of the quantity thereof.

(References: Arcana Coelestia 3104)

6624. Since man thinks on the level of the senses such things are obscure to him, so obscure indeed that he does not know what an idea is, in particular that thought is distinguished into separate ideas as speech is into words. For to man thought seems to be continuous, without separate parts; but in actual fact ideas constituting thought are the words that spirits use, and ideas constituting more internal thought are the words that angels use. And because ideas are the words they use to speak with, they are audible among spirits and angels. This explains why man's silent thought can be heard by spirits and angels, when it pleases the Lord that it should be. How perfect the ideas constituting thought are in comparison with the words composing speech may be recognized from the fact that a person can think more in a minute than he can speak or write in an hour. I have also recognized it from conversations with spirits and angels; for at such times I have in a single moment filled in the broad outlines of a subject with specific details, while my affection was engaged. The angels and spirits grasped every distinct detail, and many more that manifested themselves around that subject like a cloud.