You should know both the universal and the personal, the realm of forms and the freedom to not cling to them. The forms of the world have their place, but in another way, there is nothing there. To be free, we need to respect both of these truths.
The god of love lives in a state of need. It is a need. It is an urge. It is a homeostatic imbalance. Like hunger and thirst, it's almost impossible to stamp out.
Certainly we do not need quantum mechanics for macroscopic objects, which are well described by classical physics - this is the reason why quantum mechanics seems so foreign to our everyday existence.
A prince must be prudent enough to know how to escape the bad reputation of those vices that would lose the state for him, and must protect himself from those that will not lose it for him, if this is possible; but if he cannot, he need not concern himself unduly if he ignores these less serious vices.
Sometimes I just listen to classical pieces of music to take me away from my work. That's what I kind of do to wash away the notes that I've been working on all day. As human beings we need to sleep so that's kind of one of my little tricks.