Graphic source The full universe is Shakti which is pervaded by Shakti. Nada, Bindu, Varna are all sorts of Shakti and mixtures of these, and these combinations only will be the Shabda akin to the Artha or types of any specific Devata. The gross lettered seem is, as defined later https://damienvmbqg.tinyblogging.com/the-ultimate-guide-to-beej-mantra-67180791