In Exodus 25:4, this signifies the outermost of innocence, which is ignorance. (Arcana Coelestia 3519[8])

7915. 'And take for yourselves a member of the flock' means to receive the good of innocence. This is clear from the meaning of the Passover lamb, to which 'a member of the flock' refers here, as the good of innocence, dealt with in 3519, 3994, 7840.