'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)

'Forty' represents completeness because 'four' and 'ten' both mean what is complete. Forty is the product of four and ten. Compound numbers have a meaning similar to the simple numbers which compose them, and all numbers in the Word represent spiritual realities.

(References: Arcana Coelestia 9437; Exodus 24:18)