Jung's implication here is clearly that one should try to forget that this is only a figment or fantasy, merely make-believe—or perhaps that one should forget the “only,” the “merely”—and indeed take the fantasy seriously as a reality.
A subschool of the Illusion school of magic Figment spells produce false sensations, but no real effects of any kind (That is, a figment cannot cause damage to objects or creatures, support weight, provide nutrition, illuminate darkness, provide protection from the elements, or the like ) The accuracy of sensations produced by a figment is subject to the casters personal knowledge of the creature or item being copied All those perceiving a figment perceive the same thing
If you say that something is a figment of someone's imagination, you mean that it does not really exist and that they are just imagining it. The attack wasn't just a figment of my imagination. a figment of sb's imagination something that you imagine is real, but which does not exist (figmentum, from fingere; FIGURE)