'Must' or 'new wine' can, depending on the context, denote evil produced by falsity, or truth derived from the good of charity.

(Odkazy: Arcana Coelestia 2465)

3500. 'And go out to the field' means where a good ground exists. This is clear from the meaning of 'the field' as the good that constitutes the Church and also the good taught by doctrine, dealt with in 2971, 3196, 3310, 3317 - thus a ground that is good.