Where you just study the graphs of equations but more abstractly. Don't you think that intuitively the cartesian coordinate system makes sense but at the same time, it's arbitrary? We coulda made the left hand side the positive numbers and the right hand side the negative numbers. Graphs depend on this don't they? So why don't we abstract these ideas more? We could have really inverted and more weird graphs. Don't the picture of the graphs depend on how we define how a function is drawn?