D

Svadhisthana, the Sacral chakra, is described in classical Sanskrit tantric literature through its own seed syllable, its lotus petal count and colour, and its presiding deity, none of which reference Western musical pitch. The pairing of this chakra with the note D belongs entirely to the modern chakra-tone correspondence system that emerged from early twentieth century Theosophical writing and its later New Age elaboration, a system built by mapping an ascending Western musical scale onto the ascending sequence of chakras from base to crown rather than by any continuity with the older Sanskrit material.

Because the correspondence system treats the diatonic scale's second degree, D, as belonging to the second chakra in ascending order, the pairing is essentially positional and mnemonic rather than derived from any documented resonance or acoustic property specific to D itself; a different modern author choosing a different scale or a different note order could, and in some published alternative schemes has, produced a different pairing entirely.

Sources The Serpent PowerSir John Woodroffe (Arthur Avalon) with Rainbow Body: A History of the Western Chakra System from Blavatsky to BrennanKurt Leland

D sits a whole step above C and is the second degree of the C major scale, called Re in movable-doh solfège regardless of which key a piece is written in, since solfège names the function of a pitch within its scale rather than the pitch's fixed frequency. In the key of D major itself, however, D becomes the first degree, Do, illustrating the core distinction between the fixed letter-name system used throughout these entries and the movable, function-based solfège system Guido of Arezzo's eleventh century mnemonic eventually became.

D major and D minor both hold a substantial place in the Western concert and liturgical repertoire, and D is also the pitch most commonly used for open, unstopped strings on several standard orchestral and folk instruments, a practical consideration of instrument construction and tuning that has nothing to do with any esoteric correspondence and everything to do with the physical length and tension a given string can be built to hold in tune.