He expressed himself both in learned Latin for the clergy in his tractates, and more famously in the German vernacular in his sermons. His thoughts reach heights and depths that seem uniquely his. His manner of expression is at once simple yet abstract and bold enough to prompt him to be tried for heresy in his last years. He died before a verdict was reached, but considered himself a submissive child of the Church till the end. Contemporary Eckhart's status is uncertain: Dominican order has pressed in the last decade of the 20th century for his full rehabilitation and confirmation of his theologoical orthodoxy; pope John Paul II has voiced favorable opinion on this initiative, but the affair is still confined to the corridors of the Vatican bureaucracy.
Eckhart's central doctrines
Meister Eckhart is the most influential Christian Neoplatonist, (other notable Christian speculative mystics influenced by Neoplatonism include Blessed John of Ruysbroeck, Heinrich Suso, Johann Tauler and Angelus Silesius). Although technically a faithful Thomist (as a prominent member of the Dominican order), Eckhart had developed metaphysics and spiritual psychology of amazing boldness of expression, surprising richness of insight and enduring power of mythic imagery. Not surprisingly, major German philosophers, from Hegel to Heidegger have drunk from the wellspring of Eckhart's wisdom. Novel concepts Eckhart had introduced into Christian metaphysics clearly deviate from pedestrian scholastic canon: in Eckhart's vision, God is primarily fertile. Out of overabundance of love the fertile God gives birth to the Son, Logos Christ. Clearly (aside from a rather striking metaphor of "fertility"), this is rooted in Neoplatonic notion of "overflow" of the One that cannot hold back its abundance of Being. Just, as a Christian, Eckhart had imagined the creation not as a sort of almost "compulsory" overflowing (a metaphor based on a common hydrodynamic picture), but as the free act of will of Trinitary God. Another bold assertion is Eckhart's distinction between God and Godhead (Gottheit in German). True, these notions had been present in the Pseudo-Dionysius's writings and John Erigena's "De divisione naturae", but it was Eckhart who, with characteristic vigor and audacity, had reshaped the germinal metaphors into profound and disturbing images of polarity between the Unmanisfest and Manifest Absolute. Eckhart's psychology and pneumatology are even more original and seminal: he distinguished (as did early Gnostics like Valentinus) between psyche and spiritual element in human being. Valentinian "spiritual seed" is equivalent to Eckhart's "fuenklein", "scintilla animae" , ground of the soul or "soul-spark", which he identifies with "Imago Dei" from the Scripture. This indestructible and divine element in human being is for Eckhart (and for the major Christian mystical theology, including Eastern Othodox concept of "synteresis") only a potentiality, a latent function that needs to be nourished by vituous living and spiritual vigilance in order to grow and expand- unlike perfect Buddha nature from Mahayana Buddhism or Atman from Hindu Vedanta. The "Imago Dei" is sometimes compared to fallen Adam, exiled from Paradise, and the New Adam, or Christ Logos, is potentially the final destination of soul-spark if it, through classic Christian spiritual stages of purificative, contemplative and illuminative life comes to the unitive life where soul-spark is self-transformed into Christ Logos. Hence the great Eckhart's saying:" God gives every Good man everything He has given to His Son".
Eckhart is also spelled Eckard, Eccard. Meister means "the Master"
Accused of heresy (because of his Neo-Platonic views) by the Catholic Church (that supposedly has Christ, who in my humble opinion is a Jewish Buddha, cf Cristian Lindtners research), Eckharts thoughts were kept under lock and key for several centuries. This is unfortunate because it meant that the Catholic Church was neglecting a very important perspective that would have allowed it's parishoners to gain a greater understanding of God and their place in relation to him. The Church decided to maintain its focus on more earthly and negative concerns (such as indulgences, focussing on Hellfire to keep the church goers in-line, etc).
Here are Arthur Schopenhauers thoughts on Eckhart:
If we turn from the forms, produced by external circumstances, and go to the root of things, we shall find that Sakyamuni and Meister Eckhart teach the same thing; only that the former dared to express his ideas plainly and positively, whereas Eckhart is obliged to clothe them in the garment of the Christian myth, and to adapt his expressions thereto.
Buddha, Eckhart and I all teach the same.