In the Human Design System, the Heart center — also called the Ego or Will center — is the smallest of the nine but carries one of the strongest themes: willpower, worth, and the material world. The system counts it among the four motor centers, the ones it describes as generating usable energy, and ties it anatomically to the heart, the stomach, the gall bladder, and the thymus gland.
In the system’s terms
The Heart is the source, in the system’s model, of ego strength — the drive to commit, to work for reward, and to prove oneself in tangible terms. It governs, in this framing, willpower and the sense of one’s own value. The system is emphatic that its motor energy is not continuously available: the Heart is described as pulsing, working in bursts, which it uses to explain why willpower cannot simply be summoned on demand. Promises, competition, and the measuring of worth all sit under this center in the system’s reading.
A defined Heart is described as a consistent, reliable willpower — a person able to commit and to follow through, with a steady sense of their own worth. An undefined or open Heart is described as lacking that fixed access, and so prone to a particular pattern: trying to prove its worth, making promises it struggles to keep, and being caught up in questions of value that are not consistently its own.
Open centers and the not-self
That pattern places the Heart squarely in the system’s doctrine of the nine centers: the open ones are where a person is said to be conditioned by their surroundings, taking in energy that is not steadily their own — the pattern the system names the not-self. The open Heart forever proving itself is one of the most cited examples in the literature, and the practice the system prescribes, deconditioning, begins from these openings.
The layer that makes such readings usable — types, strategy, and authority — was introduced only in May 1997, years into Ra Uru Hu’s teaching, a history the archive documents in ZENO and The Voice on Ibiza.
Sources: the nine centers and the not-self doctrine are described in the system’s own literature, published by Jovian Archive; the 1997 introduction of the type framework is documented from the primary record in ZENO and The Voice on Ibiza. See also the five types and deconditioning.