Mysticism in its modern sense is a word to describe the spiritual and intellectual experience of the ultimate reality, which usually means God and eternity. Many or indeed all of the great religions were born from works of legendary mystics, like Buddha, Krishna or Jesus. In Europe, gnosis has been known since the ancient times and fared well in early Christianity, but later it evolved into an academical subject, a branch of philosophy. Based on the institutionalized religion and the stable feudal structures of the Middle Ages, this Christian thought bloomed, greatly enhancing the continent's sociopolitical integrity with the works of st. Augustine, Thomas Aquinas and many others. Similarly, in the world of Islam, philosophers like Malik ibn Anas or the female Sufist poet Rabia Basri tried to define the link between Allah and mortals. Those works withstood the trial of time well beyond their authors' lives, pecoming part of their civilization's cultural heritage.