In order to communicate ideas or facts to one another, we must use language. Within our language, there are several thousand words that represent several thousand ideas and objects. The words that represent ideas, feelings, etc., we call "abstract." Those that represent facts or things are known as "concrete."

     Abstract words are used to describe those things that we cannot fully understand. The nature of an abstraction is to never be completely describable or even to be thought of as the same by two people. Any emotion or belief is an abstraction: love, hate, God, time. Abstractions are not something that can be held in the hand or otherwise acknowledged with the senses.

     That which is concrete can be seen, felt, smelt, hit, tasted, eaten, heard, combed, ridden, built, or walked on. It is something that can be touched or proven with data: dates of birth, the weight of a piano, the length of a chair leg, a birth, a piano, a chair leg. These are things that are easily understood by all to be the same (although with adjectives we can distinguish a human birth from a hippo and a Chippendale from a Heppler White.)

     Some words serve a dual purpose as abstractions and concrete words. A man’s death can be observed and located in time and space. We do not yet know, however, what death is, what time is, what is truly a man, or whether we truly observe or just convince others that we observe. The mind of man is too limited and his lines of communication too poor to be able to tell for sure what is real and unreal, concrete and abstract.