Gnosis is a feminine Greek noun which means "knowledge" or "awareness." It is often used for personal knowledge compared with intellectual knowledge ( eídein), as with the Frenchconnaître compared with savoir, the Spanishconocer compared with saber, the Italianconoscere compared with sapere, the Germankennen rather than wissen, or the Modern Greek ? compared with ?.
A related term is the adjective gnostikos, "cognitive", a reasonably common adjective in Classical Greek.Plato uses the plural adjective "" - gnostikoi and the singular feminine adjective " " - gnostike episteme in his Politikos where Gnostike episteme was also used to indicate one's aptitude. The terms do not appear to indicate any mystic, esoteric or hidden meaning in the works of Plato, but instead expressed a sort of higher intelligence and ability analogous to talent.
Plato The Statesman 258e
-- Stranger: In this way, then, divide all science into two arts, calling the one practical (praktikos), and the other purely intellectual (gnostikos).
Younger Socrates: Let us assume that all science is one and that these are its two forms.
Gnosis is used throughout Greek philosophy as a technical term for experiential knowledge (see gnosiology) in contrast to theoretical knowledge or epistemology. The term is also related to the study of knowledge retention or memory (see also cognition), in relation to ontic or ontological, which is how something actually is rather than how something is captured (abstraction) and stored (memory) in the mind.
Cardiognosis ("knowledge of the heart") from Eastern Christianity related to the tradition of the starets and in Roman Catholic theology is the view that only God knows the condition of one's relationship with God.
In the Philokalia, it is emphasized that such knowledge is not secret knowledge but rather a maturing, transcendent form of knowledge derived from contemplation (theoria resulting from practice of hesychasm), since knowledge cannot truly be derived from knowledge, but rather, knowledge can only be derived from theoria (to witness, see (vision) or experience). Knowledge, thus plays an important role in relation to theosis (deification/personal relationship with God) and theoria (revelation of the divine, vision of God). Gnosis, as the proper use of the spiritual or noetic faculty plays an important role in Orthodox Christian theology. Its importance in the economy of salvation is discussed periodically in the Philokalia where as direct, personal knowledge of God (noesis; see also Noema) it is distinguished from ordinary epistemological knowledge (episteme--i.e., speculative philosophy).
Knowledge (or gnosis) in Sufism refers to knowledge of self and god. The gnostic is called al-arif bi'lah or "one who knows by God". The goal of the Sufi practitioner is to remove inner obstacles to the knowledge of god. Sufism, understood as the quest for Truth, is to seek for the separate existence of the Self to be consumed by Truth, as stated by the Sufi poet Mansur al-Hallaj, who was executed for saying "I am the Truth" (ana'l haqq).
Ginan, which literally translates to gnosis, refers to a collection of literature that is respected by the Ismailis. The Ismaili P?r ?asan Kab?r al-D?n writes that the gnostic can be compared to the lotus flower (kamal), a delicate flower with white petals that blooms in dirty swamps, and is commonly associated with beauty and purity. The flower is above the polluted swamps, rather than feeding from it, it waits for the clean, pure rain. Similarly, the gnostic lives in the physical world, but is not of this world. He is not interested in the material pleasures of the world, and is unaffected by its glamour. The gnostic awaits the gin?n from the heavens, the life-giving water that the True Guide brings. Just like how the lotus flower would prefer death over drinking from the dirty swamp, the pure soul is unable to survive without the gin?n from the True Guide. The gnostic too, would prefer death if it cannot obtain this precious nourishment.
^A concise dictionary of theology by Gerald O'Collins, Edward G. Farrugia p. 130 Publisher: T. & T. Clark Publishers (2004) ISBN978-0-567-08354-8
^"Spiritual knowledge is the state of spiritual theoria, when one sees invisibly and hears inaudibly and comprehends incomprehensibly the glory of God. Precisely then comprehension ceases and, what is more, he understands that he does not understand. Within the vision of the uncreated Light man also sees angels and Saints and, in general, he experiences communion with the angels and the Saints. He is then certain that resurrection exists. This is the spiritual knowledge which all the holy Prophets, the Apostles, Martyrs, ascetics and all the Saints of the Church had. The teachings of the Saints are an offspring of this spiritual knowledge. And, naturally, as we said earlier, spiritual knowledge is a fruit of the vision of God. "THE ILLNESS AND CURE OF THE SOUL" Metropolitan Hierotheos of Nafpaktos 
^St. Symeon the New Theologian in Practical & Theological Discourses, 1.1 The Philokalia Volume Four: When men search for God with their bodily eyes they find Him nowhere, for He is invisible. But for those who ponder in the Spirit He is present everywhere. He is in all, yet beyond all
^Faith And Science In Orthodox Gnosiology And Methodology by George Metallinos
"The scientist and professor of the knowledge of the Uncreated, in the Orthodox Tradition, is the Geron/Starets (the Elder or Spiritual Father), the guide or "teacher of the desert." The recording of both types of knowledge presupposes empirical knowledge of the phenomenon.
The same holds true in the field of science, where only the specialist understands the research of other scientists of the same field. The adoption of conclusions or findings of a scientific branch by non-specialists (i.e. those who are unable to experimentally examine the research of the specialists) is based on the trust of the specialists credibility. Otherwise, there would be no scientific progress.
The same holds true for the science of faith. The empirical knowledge of the Saints, Prophets, Apostles, Fathers and Mothers of all ages is adopted and founded upon the same trust. The patristic tradition and the Church's Councils function on this provable experience. There is no Ecumenical Council without the presence of the glorified/deified (theoumenoi), those who see the divine (this is the problem of the councils of today!) Orthodox doctrine results from this relationship."
University of Athens - Department of Theology
^Glossary of terms from the Philokalia p. 434 the knowledge of the intellect as distinct from that of the reason(q.v.). Knowledge inspired by God, and so linked with contemplation (q.v.) and immediate spiritual perception.