In the beginning of Bava Batra the Gemara is trying to figure out if היזק ראיה שמיה היזקץ. (Damage caused by seeing is damage or not). They do this at first by looking at the Mishna
The Mishna says that if partners want to divide a court yard they build a wall.
The words the mishna uses are שרצו לעשות מחיצה (that wanted to make a division) so the question is what is a מחיצה (division)? A wall? or just some sticks stuck in the ground to show where the dividing line is. The Gemara seems to say that if the word מחיצה means a wall [גודא] then we learn from this that היזק ראיה לאו שמיה היזק ((Damage caused by seeing is not damage).
I have at this point in time no idea what the Gemara means. Does it mean that if it means a wall then there is no proof one way or the other. Only if it means a division then we can deduce that היזק ראיה שמיה היזק. Or does it mean there is an actual proof?


I think it is possible that the gemara is thinking like this: If the Mishna would hold היזק ראיה שמיה היזק then it would have written השותפים שרצו ליחלק בונים כותל. That is to say it had an easy way of adding a little more information. But it choose not to do so. Therefore it must hold לאו שמיה היזק