“Self-realization and self-fulfilment are the sine qua non for human existence.”

“La inconciencia o no conciencia es la condición sine qua non para la felicidad.”

“Taking charge of your own learning is a part of taking charge of your life, which is the sine qua non in becoming an integrated person.”

“Isolation, for him, had become a basic sine qua non for existence and loneliness, his sole companion like a perfectly faithful twin. He was someone for whom even happiness would cry for, mourning the death of his sentiments and murdering the existence of his soul.”

“The essence of chastity is not the suppression of lust, but the total orientation of one's life towards a goal. Without such a goal, chastity is bound to become ridiculous. Chastity is the sine qua non of lucidity and concentration.”

“When the healthy pursuit of self-interest and self-realization turns into self-absorption, other people can lose their intrinsic value in our eyes and become mere means to the fulfillment of our needs and desires.”