The cause of all these sufferings is our fundamental insecurity. We are always wondering whether we exist or not. Our ego, or rather our attachment to the idea of self, is completely insecure about its own existence. Our ego may seem strong but it is actually quite shaky. Of course, we do not ask such questions consciously, but we always have a subconscious feeling of insecurity about whether we exist.

– Dzongsar Khyentse Rinpoche