Know thyself

Christian, Jewish and Islamic authors found various scriptural equivalents for the maxim, allowing them to discuss the topic of self-knowledge without reference to the pagan inscription.

It was frequently quoted in German philosophy and literature, by authors such as Kant, Hegel and Goethe; it was cited as an analogue of "tat tvam asi" ("that thou art"), one of the "Great Sayings" of Hinduism; and it took on an important role in the developing discipline of psychoanalysis, where it was interpreted as an injunction to understand the unconscious mind.

According to ancient Greek and Roman authors, there were three maxims prominently inscribed upon the Temple of Apollo at Delphi: "know thyself", "nothing too much" and "give a pledge and trouble is at hand".

[1][b] Their exact location is uncertain; they are variously stated to have been on the wall of the pronaos (forecourt), on a column, on a doorpost, on the temple front, or on the propylaea (gateway).

[7] Clearchus of Soli, among others, attempted to reconcile the two accounts by claiming that Chilon, enquiring of the oracle what was best to be learnt, received the answer "know thyself", and subsequently adopted the maxim as his own.

[13][c] According to classicist Charles H. Kahn, this fragment echoes a traditional belief that "know thyself" had an essentially similar meaning to the second Delphic maxim, "nothing too much"; both sayings might be considered alternative ways of describing the virtue of sophrosyne (lit.

[13] In another fragment (B112), Heraclitus defines sophrosyne as the art of "perceiving things according to their nature",[14] apparently referring to the perception of objective, material facts.

"[19] Again, it is not possible to infer from this what sort of task "knowing oneself" was understood to be, except that it was something extremely difficult to accomplish, but the fragment bears testimony to the fact that the phrase was a well-known saying during Ion's lifetime.

[24] In another work of Xenophon, the Cyropaedia, the Lydian king Croesus is captured in battle by Cyrus, and laments his failure to follow the advice of the oracle at Delphi, who had told him that he must know himself in order to be happy.

[28] A related usage, possibly inspired by Stoic philosophy, takes the phrase as a memento mori, i.e. "know that you are mortal"; it is quoted with this application by authors including Menander, Seneca, Plutarch and Lucian.

In Charmides 164d–165a, Critias argues that self-knowledge is the same as sophrosyne (as discussed above, this word literally means "soundness of mind", but is usually translated "temperance" or "self-control").

[e] However, the work inspired later writers such as Porphyry, Philostratus and Olympiodorus to connect the maxim not only with temperance but also with the other cardinal virtues of courage, justice and wisdom.

On the first occasion (124b), Socrates uses the maxim in its traditional sense of "know your limits", advising Alcibiades to measure his strengths against those of his opponents before pitting himself against them.

[46] The physician Galen (129 – c. 216 AD) employs it in this sense in his work On the Diagnosis and Cure of the Soul's Passions, where he observes that those who are the most prone to error are the least aware of their own failings.

[47] In the Magna Moralia (traditionally attributed to Aristotle), it is pointed out that people frequently criticize others for faults of which they themselves are guilty, and this is presented as evidence for the claim that to know oneself is difficult.

For a friend is, as we assert, another I.Stoicism – a school of philosophy founded by Zeno of Citium in the early 3rd century BC – placed great emphasis on "know thyself", making this the very essence of wisdom.

[51] After a brief discourse on the advantages of virtue, Cicero continues:[51] When this man shall have surveyed the heavens, the earth, and the seas, and studied the nature of all things, and informed himself from whence they have been generated, to what state they will return, and of the time and manner of their dissolution, and has learnt to distinguish what parts of them are mortal and perishable, and what divine and eternal — when he shall have almost attained to a knowledge of that Being who superintends and governs these things, and shall look on himself as not confined within the walls of one city, or as the member of any particular community, but as a citizen of the whole universe, considered as a single Commonwealth: amid such a grand magnificence of things as this, and such a prospect and knowledge of nature, what a knowledge of himself, O ye immortal Gods, will a man arrive at!

[57] Clement of Alexandria (c. 150 – c. 215 AD) attempts to prove in the Stromata that the Greeks derived their wisdom from the Hebrew scriptures, and in this connection cites numerous Bible passages which he believes may have inspired the Delphic maxims.

[67] One way in which Islamic scholars understood the message of the maxim was to associate it, as did the Christian authors, with the idea that mankind was created in the image of Allah.

[68] In the 13th century, Jewish philosopher Isaac Albalag brought the Arabic saying quoted by Avicenna into connection with a verse from the Book of Job (19:26): "From my flesh I behold God".

"[72] Another concept discussed by Porphyry in this work, followed up by both Jewish and Islamic authors, is that the true self is identical with the intellect, as contrasted with sensation or passion.

In religious contexts, the maxim continued to carry the same connotations that it had held for the early Christians, with the understanding that to know oneself was either a route to, or synonymous with, knowledge of God.

John Calvin's explanation of the importance of self-knowledge in Institutes of the Christian Religion (1536) is typical of the manner in which the topic was discussed by theologians of the era:[74][75] With good reason the ancient proverb strongly recommended knowledge of self to man ...

[79] Other writers of the period also emphasized the social dimension of self-knowledge; Thomas Elyot linked the maxim to the Biblical commandment "Love thy neighbour as thyself", and Samuel Pufendorf argued that one should know oneself to be a member of society and obey the laws created for the common good.

[82] The Lutheran reformer Philip Melanchthon, in his 1550 oration on anatomy,[i] wrote as follows:[83] It is a matter altogether worthy of man to behold the nature of things, and not to spurn the contemplation of this wonderful work of the world which ... should remind us of God and of His will.

Some argued that man should not seek to know himself at all; Irish poet James Henry contrasted this command of Apollo with the warning of the Christian God to "touch not the tree of knowledge", while Samuel Taylor Coleridge ended a short poem on the subject of the maxim with the lines:[100] Vain sister of the worm,—life, death, soul, clod– Ignore thyself, and strive to know thy God!

Richard Wagner, in the above-mentioned essay, was the first to explicitly make this connection, although he claimed that the link was implicitly present in the work of philosopher Arthur Schopenhauer.

This concept continued to inspire Western authors into the 20th century, and the Delphic precept was increasingly reframed as a proclamation of the oneness of the individual with his neighbour and with God.

The founder of the discipline, Sigmund Freud, quoted the maxim only once, in The Psychopathology of Everyday Life (1901), but in later decades it became a common assertion among practitioners in the field that to know oneself means to understand one's unconscious mind.

[103] Certain branches of psychoanalysis, based around object relations theory, focus on the role of interpersonal relationships in the development of the ego, allowing this application of the maxim to incorporate the idea that self-knowledge depends upon knowledge of others.