PD03. The limit of quantity in pleasures is the removal of all that is painful.
An analogy would be that this folding yardstick pictured below is the feeling of "pleasure," a tool by which we measure how long , or how desirable, something is. The "limit of pleasure" would be a reference to this tool, straightened out to its maximum extent, at which it measures the largest quantity of pleasure that is possible to measure. At that point, there is no more crookedness ("pain") left in the tool, the pain is totally gone.
This analogy helps us draw many important conclusions in intellectual debates, but tells us exactly nothing about what we are using the yardstick to measure. The tools of precision tell us nothing about the type or purpose of the wall we are building. What we are measuring is the way we spend our time while we are alive, and that is going to vary for each of us according to our individual circumstances.
We don't obsess over yardsticks, and we should not obsess over the "limits" of pleasure as a measurement. We simply use the yardstick of pleasure to construct the most pleasant life that is possible to us given our individual circumstances.