How times change. At this time of year, hundreds of universities and other educational institutions across America are holding their own commencement rituals. And, as in Marshall's time, these are solemn, high-stakes events. Little surprise: in modern America, commencement ceremonies have almost become akin to “coming of age” ceremonies. As an anthropologist might say, they are a liminal ritual that marks a changing social state, and thus forces people to reflect on the values they want to inculcate in the next generation.

But if Marshall could have heard this year's crop of commencement speeches - or secular “sermons” - he might have been shocked. Never mind the fact that modern etiquette demands that today's commencement speeches are very short, usually lasting a mere 12-15 minutes; and ignore the fact that the speeches are now deliberately directed at students, not society as a whole. What is really striking is that the ranks of civic notables who are delivering these sermons are no longer limited to senior politicians or even judges and religious leaders.

On the contrary, writers, business leaders, sportsmen, TV personalities, entertainers and scientists now dominate the ranks. Thus students this year have heard from people such as Oprah Winfrey (chat-show host); Jim Yong Kim (head of the World Bank); Julie Andrews (actress); Annie Lennox (singer); Neil deGrasse Tyson (astrophysicist); the Dalai Lama (the Buddhist leader); Arianna Huffington (journalist); and Sheri McCoy (CEO of Avon Products). True, there have been some politicians and senior government officials: Barack Obama, Cory Booker, Kirsten Gillibrand and Michael Bloomberg have spoken too. But after perusing the numbers, it seems to me that the statesmen were vastly outnumbered by cultural commentators. (In the interests of disclosure I should admit that I have skewed that list too, since I was one of several journalists who spoke, in my case at Baruch College in New York.)

And there is another shift too: the “me” factor. Five or six decades ago, statesmen did not usually talk about themselves in public. They preferred to focus on lofty policy ideas. These days, some politicians still discuss politics. But most do not: instead, the overriding fashion for speakers is to talk about their own inner journeys and individual struggles. Steve Jobs, the late founder of Apple, did this particularly brilliantly in 2005 when he told Stanford students about how cancer, career twists and marriage had shaped his life. “Your time is limited, so don't waste it living someone else's life,” he advised. But numerous actors, writers and other speakers have done the same. This year's address to the University of Michigan by Twitter CEO Dick Costolo explained to students how career failure had made him more creative, and left him convinced that “you can't plan a script” for life and just have to “be in this moment”. In place of high-policy plans to rescue Europe, in other words, there is personal, self-help philosophy. I dare say some FT readers might feel somewhat appalled by this. After all, the changing tone partly reflects the fact we live in a more individualistic, entertainment-obsessed, consumer-focused age, where students expect advice to be given in bite-sized chunks, with a lacing of emotion to grab their attention. But there is a more optimistic interpretation: the shift also reflects a more inclusive, egalitarian age. Six decades ago, statesmen such as Marshall inhabited a world that was distant from most people's lives. The boundaries between politicians, public intellectuals, entertainers and business leaders are blurring. Politicians today might feel pressure to talk about their “private lives”; but actors, singers and chat-show hosts also face pressure to take a stance on “public” issues and civic questions - be that in commencement sermons or anywhere else.

Of course, it is an open question whether any students ever actually listen to any of this; far less remember it later. Most of the graduates are pretty bleary-eyed and relieved by the time they get into that stadium; their parents doubly so. But perhaps the real value of all those speeches-cum-sermons is that they are collectively creating an extraordinary body of literature that will enable future historians to study how America's leaders wanted to present themselves in the 20th and 21st centuries. As such, it is a peculiarly admirable tradition. Even - or particularly - in an age when a 13-minute speech has come to seem to many graduates as if it is “l(fā)ong”.