It is recorded that the serpent tempted Eve and made her commit sin (Gen. 3:4-7). That serpent could converse with man and also knew God's intention to prohibit man from eating the fruit of the Tree of the Knowledge of Good and Evil. Thus, the serpent must have been a spiritual being in their immediate environment. Rev. 12:9 says, "And the great dragon was thrown down, that ancient serpent, who is called the Devil and Satan, the deceiver of the whole world." This indicates that the serpent is called the Devil and that this "ancient serpent" is the very one who tempted Eve. The Bible says further that the serpent was thrown down from heaven, therefore we must again say he must be a spiritual being. 

In order to know who the serpent was, we must know who Satan is; therefore we must determine who was that spiritual being thrown down from heaven. That serpent who was thrown down from heaven must originally have been created as a good being headed toward perfection. There was no one in the Garden of Eden not created by God; furthermore, no being already perfect could be capable of falling and committing sin.