It has been said that no room is big enough for two university principals. This is not an observation on the bloating effect of all the official dinners they have to attend, but a scurrilous allegation that their role as academic leaders requires an inflated ego.
Discretion - and the laws of libel - prevent me from embarking on a series of psychological case studies involving principals I have known. Instead, let me comment on two public lectures that I recently attended, each given by a former university principal (in separate rooms) and each raising interesting issues about the purpose and direction of education.
Sir Kenneth Calman, chancellor of the University of Glasgow, gave this year's Stanley Nisbet Lecture on "The Role of the University in the 21st Century". In a wide-ranging analysis, he emphasised the importance of generating and disseminating knowledge, contributing to public policy and upholding the values of a civilised society.
Drawing not only on his own background in medicine, but also on his attempts to promote inter-disciplinary studies while principal of Durham University, he gave many examples of good practice in learning and teaching. While acknowledging the financial and bureaucratic pressures to which universities have been subject in recent years, he argued that they still make an immensely valuable contribution to the public good and that their historical and contemporary significance should not be underestimated.
A rather different perspective was given by Sir Graham Hills, former principal of Strathclyde University, at this year's Stow Lecture. Under the title "Knowledge is Luggage: Travel Light", Sir Graham argued that the traditional function of universities - transmitting knowledge - has been overtaken by technology and that all the effort of the past to memorise and reproduce facts is no longer necessary.
Instead, he argued for a shift of emphasis towards the development of a range of skills that could be applied in ways that would benefit the individual, community and society as a whole. Thus the future will depend much more on skills of communication, creativity and enterprise than on the possession of abstract knowledge, which can now easily be accessed via the internet.
In a very arresting metaphor, Sir Graham said that, in future, books would be regarded as "coffins for words" and libraries "cemeteries for books". As someone who has spent more time reading than is probably healthy, this was a disturbing thought, but it served as a reminder that even very well-established formats, such as the printed word, do not have an indefinite shelf-life. Sir Graham argued that the pace of change would mean that many of our most cherished orthodoxies about the purposes of education would need to be revised.
He was being deliberately provocative and, under questioning, conceded that the contrast between knowledge and skills could be over-stated. In order to apply skills intelligently, it is usually necessary to have a good foundation in formal knowledge - this is true, for example, of the work of doctors, lawyers and engineers.
But, even with this important qualification, the implications for teachers are considerable. The basis of entry to secondary teaching - subject knowledge in one or more disciplines - may need to be reviewed. That, in turn, would raise interesting issues for pedagogy and assessment.