  Bacon's manuscripts already mention the doctrine of the idols as a necessary condition for constituting scientia operativa. In Cogitata et Visa he compares deductive logic as used by the scholastics to a spider's web, which is drawn out of its own entrails, whereas the bee is introduced as an image of scientia operativa. Like a bee, the empiricist, by means of his inductive method, collects the natural matter or products and then works them up into knowledge in order to produce honey, which is useful for healthy nutrition.