Meaning of Anxiety

I saw that all the things I feared and which feared me had nothing good or bad in them save in so far as the mind was affected by them.-Spinoza, Treatise on the Correction of the Understanding. I would say that learning to know anxiety is an adventure which every man has to affront if he would not go to perdition either by not having known anxiety or by sinking under it. He therefore who has learned rightly to be anxious has learned the most important thing.-Kierkegaard, The Concept of Dread. ... one thing is certain, that the problem of anxiety is a nodal point, linking up all kinds of most important questions; a riddle, of which the solution must cast a flood of light upon our whole mental life.-Freud, General Introduction to Psychoanalysis.