Each plank in the walls of the Mishkan had two pegs on the bottom. These pegs fit into the adanim, a pair of silver sockets for each plank. The Chasam Sofer says that these planks are symbolic of Man, who stands on two legs.
Beneath him are two silver sockets representing his two inclinations, his “good” yetzer tov and his “evil” yetzer hara. Man’s goal is to be a master over both of these forces, using them both to serve HaShem.
These sockets were made of the silver given in the form of the machtzis ha-shekel, the half-shekel each person gave when the Jews were counted. It is quite fitting that this was the purpose for which this donation was used.
Just as a person has two inclinations pushing him in opposite directions and he must choose which way he follows, money can be a tool for extreme good or extreme evil. It is up to a person to ensure he does what is right with his money and be a master over it, rather than the other way around.
