Analysis (scientific) would describe the one fancy, the other. divides wholes into parts, and combines those parts, selected arbitrarily, into new wholes e.g. The second, by a union of perception and fancy, produces fictions out of realities, i.e. The first is the faculty which analyses and elucidates the view of things undissected and in the gross ( ὁ λοσχερῆ): whereby a simple phenomenon becomes complex speculatively: for instance, man becomes a compound of soul and body. It must therefore be something more spontaneous than ratiocination, whether deductive or inductive while it is more reliable than Fancy or Imagination. By means of it and entertainer might amuse an audience with fire-breathing monsters, men enfolded in the coils of serpents, etc.
But then Gregory does not deny that lying wonders are also fabricated by it. Induction might almost represent this view of it. Any one who should judge this faculty more precious than any other with the exercise of which we are gifted would not be far mistaken. He instances Ontology (!), Arithmetic, Geometry, on the one hand, Agriculture, Navigation, Horology, on the other, as the result of it. According to my account, it is the method by which we discover things that are unknown, going on to further discoveries, by means of what adjoins and follows from our first perception with regard to the thing studied.
But Gregory ascribes every art and every science to the play of this faculty. Fancy, or notion, would thus represent Eunomius' view of it. He instances colossi, pigmies, centaurs, as the result of this mental operation. He reduces its force to its lowest level, and makes it only fancy the unnatural, either contracting or extending the limits of nature, or putting heterogeneous notions together. Eunomius, Gregory says, makes a solemn travesty of the word. It is important, for the understanding of the following Book, to determine what faculty of the mind ᾿ Επίνοια is.