If you have 4 quarter notes in a measure, in 4/4 time, the quarter notes occur on the beats (i.e., 1, 2, 3, 4) and I would think that the first beat occurs at the onset of the measure. That is, there is no delay between the onset of the measure and the first beat of that measure. However, when you see sheet music, there is space between the vertical line that indicates the beginning of the measure and the first note. Is that just a concession to graphical clarity, or am I wrong in my belief that the first beat occurs at the very beginning of the measure? Thanks.