The word quixotic means “foolishly impractical especially in the pursuit of ideals.” However, when I think of Don Quixote, this is not what I think. Instead, I think of wonderfully twisted logic to justify crazy behavior.
There is no better example of this than in Chapter 21 of Don Quixote. In it, a barber is traveling to work on his mule. On top of his head, he wears his wash basin to protect his head from the rain. However, Don Quixote sees this and thinks that it is the mythical helmet of Mambrino.
He must have it so he charges the unfortunate barber. On seeing the insane man with the lance attacking him, the barber flees, leaving his “helmet” and mule behind.
This would be a perfect triumph for Don Quixote, except that Sancho insist upon injecting reality into the conversation (just like a 17th century liberal):
“I was just thinking what a big pate that pagan had who owned it, for this helmet looks exactly like a barber’s basin.”
Normally, Don Quixote fights more with Sancho. In this case, he immediately provides a justification:
This is the same line he gave in Chapter 8 after mistaking the windmills for giants. Or Chapter 18 after mistaking the sheep herds for armies. Or… Don Quixote always has a reason for why he was not wrong.
And that is the way it is in life. It is only by denying responsibility that we can continue on making the same the mistakes. If Don Quixote admitted that he has a tendency to see things that aren’t there, he would have to conclude (as he does at the end of the book) that he really needs to be cared for. But he doesn’t, and that to me, is the essences of quixotic.
 That does not change the meaning of the word, of course. If you use “quixotic” in that way, people will either think that you are ignorant or as crazy as Don Quixote.
Isn’t it strange that the “x” is pronounced “j” in “Don Quixote” (as usual, more reasonably in Spanish where is it spelled “Don Quijote”) but “x” in “quixotic”? It’s enough to drive you crazy.