Sikh religion was founded conjointly by the great teachers or gurus: the line began with guru Nānak (A.D. 1469-1538) and ended with guru Govind Singh (A.D. 1666-1708).
Sikh philosophy is contained in the religious, poetic compositions (Gurbāṇī) of guru Nānak
—it is expounded in the hymns (śabads) of the other nine gurus and elucidated in the ballads (vārs) of a learned, devout Sikh, Bhai Gurdās, who was a relative and contemporary of guru Arjun, the fifth guru(A.D. 1554-1606).
The fact that guru Nānak and the other Sikh gurus chose the medium of poetry or song—every line in the Sikh Scripture (Granth Sahib) is set to music—is of great significance.
Verse and music impart to thought emotion, beauty, brevity and power, and the person who recites or sings or even devoutly listens is filled with joy and reverence.
He may find it difficult to grasp the full implications of the thought contained in the verse, and each line in the hymn may lend itself to diverse interpretations— nevertheless, the effect upon his mind is both profound and inspiring. He loses his self in devotion and rapture.
The philosophical and religious thought contained in the Gurbāṇī, in the hymns of the Sikh gurus, is the result of inspiration—revelation—and not of formal logic or reasoning.
As guru Nānak himself put it:
“I relate as the divine word (the vāṇī of my Master) comes to me.”
The hymns are born of an inner illumination—of the spirit becoming in tune with the Infinite. They are the outpourings of a divinely inspired heart and it is they that deserve the name of divine or spiritual philosophy.
Guru Nānak's philosophy was not something distinct or apart from his religion or ethics—they were all one in his mind—Knowledge, Truth, Goodness and God.
Sat (Truth) was bound up with Sat-nām, the holy name of the holiest being and with Sat-ācār or the right conduct, thus co-ordinating Truth with Goodness, the two supreme values of life.
Writes guru Nānak:
“Truth is higher than everything but higher still is true conduct.”
The man of right conduct and culture is the man of right intuition, and the saint is our best philosopher and guide; for light descends on him from on High, as divine grace.
Guru Nānak dealt with problems of philosophy as they arose in his mind or in his conversations or disputations with saints of other persuasions and an attempt has been made in later sections to state the views of guru Nānak in his own words.
Guru Nānak believed in enquiring into the value(qimat)—it is a Persian word that he uses—of every human action: its value for the time-being or its human value as well as its eternal or divine value.
According to him, human values are derived from man-in- himself and all enduring values from man-in-reality or man-in-God.
Reality is realizable only in and through such a valuable life—which is a glory to itself and a glory to God. The Sikh gurus lived such a life, and the truths of philosophy—the most uncompromising of them—are illustrated in their lives.