Could the process of star formation in a collapsing gas cloud transform the process of virialisation and ultimately promote the formation of a central black hole? Consider the following idealised and oversimplified scenario. Suppose a gas cloud massive enough to generate vast numbers of stars is drawn together by gravity. Variations in density from place to place may cause overdense regions of the cloud to collapse into stars. In this process the escape into intergalactic space of radiation from such individual overdense regions promotes the virialisation of stellar matter and the formation of stable stars. But once matter has precipitated into stars, the cloud, now composed of infalling stellar particles, as it were, can only be virialised by the escape from the cloud of the surplus kinetic energy of the particles themselves, i.e. of whole stars. Until this happens collapse must proceed adiabatically. Star formation thus quenches virialisation of the cloud as a whole and promotes adiabatic collapse. Eventually, however, the density of infalling stars must become high enough for close encounters between stars to become common. A new mechanism for virialisation of the cloud can now activated. Tidal kneading during close encounters between stars renders such encounters inelastic, and tranforms surplus kinetic energy of stellar motion into radiation which can escape from the cloud. The dissipation of surplus kinetic energy can gradually damp out any adiabatic oscillations and the star cloud as a whole can eventually settle into a stable and localised configuration. The end result might be a globular cluster of stars. But if the collapsing gas cloud were massive enough to generate billions of stars the density of stars in a central adiabatically-collapsing region might become large enough for an event horizon to form, in which case the collapsing cloud of stars could acquire a black hole at its centre, as its core collapses towards a singularity. Is it possible that the classical virial theorem is at the heart of the pervasive presence of black holes at the centres of galaxies?