It's from Robert's Rules of Order. In most Ordinary Societies of the time, there would be a literal table, chair, and floor. The chairman would sit in the chair at the table with the VP and Secretary, and you would get the floor to speak -- literally stand in the open spot on the floor. If you wanted to make a motion, you would bring the motion to the table -- literally -- and it would be debated. If the society decided to leave it alone and come back to it later, they would put it on the table -- literally, take the paper with the motion on it and leave it on the table for later.