Certainty undermined by doubt

 As my certainty increases, my doubt decreases; conversely, as my doubt increases, my certainty decreases

Some people who meditate claim  they experience  moments of certainty, it is as if my perception is guided by “a great light in the intellect” 

'This rational illumination empowers me to “see utterly clearly with my mind’s eye my feelings of certainty are grounded....' claims one -smacking of Descartes.