A scale is an graduated sequence of degrees measuring some kind of quality or quantity. For our purposes we would mostly be interested in ascending scales indicating personal sanity, well-being or vitality. If we can lay out certain desirable qualities on scales, that gives us something to steer by. We would know if we are going in the right direction. Before we get too far into that, let me warn you that life isn't really linear.
Life is lived in many more dimensions than one.
So, any linear scale is at best a crude approximation with only limited applicability. Don't make the mistake of believing that a person really IS somewhere on a linear scale. Any person is a complex, dynamic, multi-dimensional event. Sometimes it is practical to plot a person on a scale within a limited context, with the purpose of improving her state. But that is all it is done for.