The Sacral centre is one of the nine centres of the Human Design bodygraph. Human Design is a modern esoteric system, originated in 1987 by Ra Uru Hu (born Alan Robert Krakower, 1948-2011), who presented its content as received teaching rather than as an inherited tradition. It is roughly four decades old and is best read as a contemporary synthesis, not as ancient wisdom or established fact. Ra Uru Hu combined four older systems that had never before been joined: the I Ching supplies the sixty-four gates, the Hindu chakra model the nine centres, the Kabbalistic Tree of Life the connecting channels, and Western astrology the method of calculation.
Where the Hindu chakra model it draws on has seven centres, Human Design maps nine, a difference the system explains by a claimed mutation in human form, a claim about the species that has no support outside the system and should be reported as its own, not as fact. In the model the Sacral centre is classed as a "Motor" centre and is the motor of life force, work and reproduction, treated as the engine of vitality and sustainable energy. A centre may be "defined" (consistently active) or "undefined" (open and conditioned by others) in a given chart. These are features of a contemporary esoteric framework dating from 1987, described here as the system presents them.
Sources The Human Design SystemRa Uru Hu (Alan Robert Krakower) with Über den Tellerrand, ein Blick ins Human Design System (HDS)Petra Stute, Virineya Würgler and Johnny Würgler