What Is Spirit?

Joseph grobawski asked, what is spirit exactly? We speak of the godhead and angelic creatures having a spiritual nature. Sometimes the soul is conceived of as spiritual, yet other times the soul is called the form of the body and the principle of life for the body. And it clearly isn't the same stuff as god and angels. God doesn't even consist of stuff in that sense. Even the three persons of the trinity are not parts of god. A person is not a part.