  A brief summary is given of an alternative interpretation of the Event
Horizon Telescope observations of the massive black hole in the nucleus of the
nearby galaxy M87. It is proposed that the flow is primarily powered by the
black hole rotation, not the release of gravitational energy by the infalling
gas. Consequently, the observed millimetre emission is produced by an
"ergomagnetosphere" that connects the black hole horizon to an "ejection disk"
from which most of the gas supplied at a remote "magnetopause" is lost through
a magnetocentrifugal wind. It is argued that the boundary conditions at high
latitude on the magnetopause play a crucial role in the collimation of the
relativistic jets. The application of these ideas to other types of source is
briefly discussed.
