What does "There is always some madness in love. But there is also always some reason in madness." mean?

That the insane usually have their own reasoning. It may only make sense to them or be based on flawed assumptions.

Everybody is (in various degrees) crazy, especially when they are, or think they are, in love.

When I was religious, I used to say I didn’t believe in true evil, because even Lucifer believed he was right and justified in what he did.

I still don’t believe in “evil”, but my reasoning isn’t based on Lucifer anymore.

^^^ Since I found that God is Lovingkindness,
I realized even bad ole Lucifer is forgiven, in the end!

Initially one loves another out of a delusional belief that they fulfilled and completed them. Love can emerge from this madness. Over time, if one is mature enough, they come to recognize their differences and see that they complimented each other. We all have faults. Unless a fault is unacceptable, it can be overlooked.

A few years ago, when my hair was still dark brown, our community theater company cast me in the role of Dracula. To portray him successfully, I could not see Dracula as mad or evil, but instead recognize that he saw himself as a superior being who regarded lessor humans as cattle.

@Dan_Lyons – Not everything is an invitation to preach at me. Seriously.

Anything that we commit ourselves to has a degree of madness in the sense that there is no scientific reason for why we should be committing to one thing instead of something else.

Although madness is present in all societies, the form that it takes is culturally dependent. For example, it not just coincidental that so many recent mass murders in industrialized nations were done by young white bigoted males at a time that there has been a steady decline in the WASP portion of the population..