This is not intended to be an all inclusive listing of ancient spiritual wisdom. Rather, what we are including here are those things that we believe directly relate to the modern spiritual tradition that is called New Thought. Also, the label on this page raises the question, what is ancient? Here we are considering it to be those things that originated over at least 1000 years ago, most are much older.
Greek philosopher Plato is long considered to be one of the original thinkers offering ideas that have grown into what is now known as New Thought. Per Brittanica Encyclopedia website: “Elements of New Thought may be traced to Platonism, based on the Idealism of the 5th–4th-century-BC Greek philosopher Plato, who held that the realm of ideas is more real than that of matter; to Swedenborgianism, especially Swedenborg’s view that the material realm is one of effects whose causes are spiritual and whose purpose is divine; to Hegelianism, based on the views of the 18th–19th-century German philosopher G.W.F. Hegel, especially those concerning the external world, mental phenomena, and the nervous organism as the meeting ground of the body and the mind; to Orientalism, involving spiritual teachings of Eastern religions (e.g., Hinduism); and, particularly, to the Transcendentalism (a form of Idealism) of the 19th-century American philosopher and poet Ralph Waldo Emerson.”
A Few Helpful Resources:
Wikipedia article on the Allegory of the Cave
Antecedents of New Thought: Plato (Unity minister audio talk)
Plotinus is considered to be the founder of Neoplatonism and one of the major influences on New Thought proponents.. Taking his lead from his reading of Plato, Plotinus developed a complex spiritual cosmology involving three foundational elements: the One, the Intelligence, and the Soul. It is from the productive unity of these three Beings that all existence emanates, according to Plotinus. The principal of emanation is not simply causal, but also contemplative. Plotinus taught that there is a supreme, totally transcendent “One”, containing no division, multiplicity, or distinction; beyond all categories of being and non-being. His “One” “cannot be any existing thing”, nor is it merely the sum of all things (compare the Stoic doctrine of disbelief in non-material existence), but “is prior to all existents”. Plotinus identified his “One” with the concept of ‘Good’ and the principle of ‘Beauty’.
A Few Helpful Resources:
Harvard Divinity Bulletin – Nice summary of Plotinus
Antecedents of New Thought audio by Eric Butterworth on philosophers