Enclosed (enclosedletter)

Assuming a sentence rises into the air with the initial capital letter and lands with a soft-ish bump at the full stop, the humble comma can keep the sentence aloft all right, like this, UP, for hours if necessary, UP, like this, UP, sort-of bouncing, and then falling down, and then UP it goes again, assuming you have enough additional things to say, although in the end you may run out of ideas and then you have to roll along the ground with no commas at all until some sort of surface resistance takes over and you run out of steam anyway and then eventually with the help of three dots... you stop.