Regular doses of syrup of figs, fresh air, plain cooking, a tot of whisky before bedtime. Every centenarian seems to have a different explanation for their longevity.
In the case of local education authorities, the answer seems more straightforward. They have survived because they provide some services that central government has deemed essential.
As this centenary supplement makes clear, the LEAs of England and Wales are now unrecognisable from the new-borns who were slapped on the bottom in December 1902. Unrecognisable, too, from the LEAs of every other decade - particularly the self-confident and hyperactive post-war authorities that built thousands of schools for the "sons and daughters of returning heroes".
Many pundits contend that LEAs are in terminal decline. Yes, they still have many responsibilities: budget delegation to schools, employment of teachers, pupil attendance, special educational needs, school improvement, meals and transport, as well as the youth service and adult education. But they are now too feeble to counter the overweening power of central government.
There is some truth in this thesis, but it is not the whole story. LEA leaders still have some influence on the education service, particularly if they form cross-party alliances (page 4), or are fortunate enough to be Welsh (page 5).
Critics of LEAs are right to claim that they are often unduly bureaucratic.
The insightful article by York's education director, Patrick Scott, makes that clear (page 7). But some LEAs are anything but staid bureaucracies. A few have forged productive partnerships with private-sector education companies after damning inspection reports (pages 8 to 11).
And even successful authorities are experimenting with radically new models of "service delivery" that invariably involve private partners. It is difficult to say where this outburst of almost anarchic experimentation will lead. Predictions about the future of LEAs vary wildly (page 14). But one thing is clear: it is still too soon to write their obituaries.
David Budge Deputy editor, tes firstname.lastname@example.org