Words are placeholders waiting for the next word...
While you are speaking, you are seen to be creating a sentence. Like those lines of spinning upside-down plates or cups that the "magic" people arrange, each word merely holds its place until the sentence is finished.
This means that while you are working each word is provisional or active: you are still constructing. Senetences are constructed in time, not as dead things. Therefore, "sentient" which I almost wrote, is the right word. Sometimes penitent...
Anyway --- before you put me in the penitentiary --- A (The?) sentence begins with a capital letter and ends with a dot, a period. (I dont know why it's called a period.)
Sentences are not dead things, such that a person might analyze. A word that is used in a sentence is still spinning, while others are added.
If any of those words were dead you would not have a sentence. Not really. They are all somewhat living and the initial caps and final dots are more like a formality. Of course, formally, I'll be glad to admit, we do have the periods and the initial caps. This seems to regularize. Quite honestly I think this too is necessary.
It would seem to keep everybody in the society on the same level or on the same plane so they can interact with one another. It keeps everybody in line, we might say.