The Three Bodies of Buddha (I) (Trikaya in Mahayana)
The above ideas in turn led Mahayana Buddhists to the notion that behind and beyond Siddartha Gautama as a separate, historical individual is a buddha-nature not-other than the buddha-nature of the entire universe -- i.e., a cosmic buddha-nature or buddha-principle at the heart of the universe that was specially manifest as Siddhartha.
This came to be called the Dharmakaya, the dharma-body of Buddha pervading the whole of things and not-other than each particular thing.