Even so each qualitative property has a quantitative aspect in that intensity of feeling depends upon the strength of the stimulus. Perhaps mathematics can then take us further along the road to understanding. We can raise our arms at will, and if someone else raises our arms we are aware of the fact. Subjectivity Human beings can immediately distinguish between objective things, like the size of a book, and subjective effects like thinking that classical music is better than pop music. We can switch the focus of attention at will, for example we can listen to different instruments playing in an orchestra.
Causation Is the physical world causally closed, or are reports of psychokinesis etc.
Like athletes, trained meditators can focus their minds over long time intervals. The average person has a short attention span. We remember things and can usually recall them at will. Anaesthetics make us unconscious. In sleep we dream.