Knowledge comes from experiences, everybody knows that, but sometimes what you do experience, isn't true at all;
If you think of a mirror when you see a lot of shinning in the water as per your knowledge of shinning, you may fall.
Your doubts, your anxieties, your fears etc. don't exit in reality these things are products of your mere imagination;
And sometimes when you recall things from your memory, you also feel dizzy, discouraged and less in comparison.
Poetic Commentary On
Prathma Adhyaya, Samadhi
Patanjali Yoga Sutra : 1.6