Sāyaṇa (सायण, with honorific Sāyaṇācārya ; died 1387) was an important commentator on the Vedas. He flourished under King Bukka I and his successor Harihara II, in the Vijayanagar Empire of South India. He was the son of Māyaṇa, and the pupil of Vishnu Sarvajna and of Samkarananda. More than a hundred works are attributed to him, among which are commentaries on nearly all parts of the Veda; some were carried out by his pupils, and some were written in conjunction with his brother Mādhava or Vidyāraṇya-svāmin.
Sayana's major work is his Vedartha Prakasha (literally, "the meaning of the Vedas made manifest"), or commentary on the Vedas. His commentary on the Rigveda was edited by Max Müller, 1823-1900. The core portion of the commentary was likely written by Sayana himself, but it also includes contributions of his brother Mādhava, and additions by his students and later authors who wrote under Sayana's name. "Sayana" (or also Sāyaṇamādhava) by convention refers to the collective authorship of the commentary as a whole without separating such layers.
He has also written many lesser manuals called Sudhanidhis treating Prayaschitta (expiation), Yajnatantra (ritual), Purushartha (aims of human endeavour), Subhashita (Collection of moral sayings), Ayurveda (Indian traditional medicine), Sangit Sara (The essence of music), Prayaschitra, Alankara, and Dhatuvrddhi (grammar)
Speed of light
It has sometimes been suggested that Sayana was aware of the finiteness of the speed of light, or even that he approximated its value. These claims are based on the following passage (commenting on RV 1.50.4):
- "tatha ca smaryate yojananam. sahasre dve dve sate dve ca yojane ekena nimishardhena kramaman"
- तथा च स्मर्यते योजनानां सहस्त्रं द्वे द्वे शते द्वे च योजने एकेन निमिषार्धेन क्रममाण नमोऽस्तुते॥
- "[O Sun,] bow to you, you who traverse 2,202 yojanas in half a nimesha.".
Strictly speaking, Sayana here attributes a (fantastically high) speed to the Sun (Surya), not to light itself. Depending on what values one assumes for a yojana and for a nimesha, this speed corresponds to about 186,000 miles per second, roughly equal to the speed of light. This was pointed out by P.V. Vartak in his Scientific Knowledge in the Vedas (1995, p. 95).
- 1 yojana is said to comprise either 4 or 8 krosha (a cry or shout, or the range of the voice in calling); and 1 krosha (or goruta ~ as far as a cow’s lowing may be heard, or a bull’s roar) may represent either 1000 or 2000 daNDa (a rod or staff), and 1 danda represents 1 pauruSa (a man’s length) which equals 1 dhanvantara (bow-string) or dhanu (bow). 1 yojana measures either 4,000 or (more likely) 8,000 dhanus. Assuming that 1 paurusha is 6 ft long, then 1 yojana must represent a distance of about 14.6 km (or about 9 miles, as suggested by Monier-Williams).
- nimesa means shutting the eye or winking, and as a measure of time it is a wink of the eye or a moment. The Arthashastra (c. 300 BC) defines 1 nimesa as 1/360,000th of a day and night, i.e. 0.24 seconds.
- Given that 1 yojana is between 14.6 and 16.4 km, 2,202 yojanas must represent between 32,149 and 36,113 km. Half a nimesha is 0.12 seconds. Sayana thus gives the "speed of the Sun" as between 267,910 and 300,940 km/sec, i.e. the same order of magnitude as the speed of light at 299,792 km/sec.
Vartak treats this as an instance of scientific foreknowledge in the Vedas, even though the claim is not in the Vedas but in Sayana's 14th century commentary. Sayana's commentary is still 300 years older than the first known successful measurement of the speed of light. Kak points out that the Vayu Purana (ch. 50) has a comparable passage, where the "speed of the Sun" is exactly 1/18th of Sayana's value. While he is also susceptible to assuming "scientific foreknowledge" by mystical means, he also accepts that "to the rationalist" the proximity of Sayana's value to the physical constant is simply coincidence.
- Vijayanagara Literature from book History of Andhras, p. 268f.
- Encyclopaedia of Indian Literature: sasay to zorgot from book 'Encyclopaedia of Indian Literature, p. 3885f.
- Subhash Kak Indian Journal of History of Science, vol. 33, 1998, pp. 31-3; http://www.ece.lsu.edu/kak/sayana.pdf, (accessed 15 Feb 2011).
- Subhash Kak, The Speed of Light and Puranic Cosmology, Annals Bhandarkar Oriental Research Institute, vol. 80, pp. 113-123, 1999.
- Max Müller, Rig-Veda Sanskrit-Ausgabe mit Kommentar des Sayana (aus dem 14. Jh. n. Chr.), 6 vols., London 1849-75, 2nd ed. in 4 vols. London 1890 ff.
- Rgveda-Samhitā Srimat-sāyanāchārya virachita-bhāṣya-sametā, Vaidika Samśodhana Mandala, Pune-9 (2nd ed. 1972)