Hive management in early spring to speed up brood production. Propolis is another byproduct of the bee hive. Certain races of bees are more prone to using propolis. Propolis can be collected on special plastic propolis screens. The tendency of the bees is to use propolis as a glue to seal openings that are too small for a bee to crawl through. A propolis screen is usually put in place of an inner cover. It has small openings that are propolized by the bees. The propolis screen can be frozen which hardens the propolis. Once the propolis is frozen it can be
Mental substance Mental substance Mental substance is the idea held by dualists and idealists, that minds are made-up of non-physical substance. This substance is often referred to as consciousness. This is opposed to the materialists, who hold that what we normally think of as mental substance is ultimately physical matter (i.e., brains). Descartes, who was most famous for the assertion "I think therefore I am", has had a lot of influence on the mind–body problem. He describes his theory of mental substance (which he calls res cogitans distinguishing it from the "res extensa") in the "Second Meditation" (II.8) and in "Principia Philosophiae"