"May you be peaceful and prosperous, with many cattle and children."
These words mark the final blessing of a Maasai man as he moves from the brave blaze of warriorhood into the respected shade of senior elderhood.

They also end the ceaseless round of celebrations that mark the progression of an entire male generation from birth to death.

The first celebration in a man's life is the pre-circumcision ceremony, alamal Lengipaata, which is followed by emorata, his circumcision and attainment of warriorhood ceremony. Some 10-15 years later eunoto marks the stage at which an age-set retires from warriorhood, marries and settles into junior elderhood. And finally there is olngesherr, which marks the transition from junior to senior elderhood.

Occurring once a decade, this is an increasingly rare event to which ‘those who confine their farts' (the Maasai term for trouser-wearing Europeans) are rarely invited; so we felt highly privileged to witness and photograph an olngesherr enacted in the shadow of Mt Kilimanjaro earlier this year. Staged in a manyatta, a ring of mud-and-wattle huts constructed by women, the ceremony must coincide with the full moon and begin on a day considered propitious by the laibon (soothsayer). For weeks in advance, though, a procession of elders streams into the area, parading the staff of peace, their favourite wife and the most gorgeous cow they possess. Dressed to kill, they favour scarlet shukas worn toga-like and clinched with a belt, while their women wear pendulous earrings, serpentine bead coils and swathes of bright cotton.

There is much handshaking, singing and blessing as the guests arrive; then begins the stately pageant of the rituals and the serious business of the dance. Warpainted warriors form into waves; haughty profiles jut and feet thud as first one, then another, jumps ramrod straight and impossibly high into the air. On the perimeter, the maidens flutter and those whose jumping days are done feast or hold council.

The Maasai believe that all the cattle in the world are theirs by God-given right, so most of their ceremonies centre on these beloved creatures. In this case, an unblemished bull has been selected and showered with extravagant praise and adulation for several weeks in advance of its demise. Now, flanked by a bovine guard of honour, led by a cordon of elders and fèted and blessed along its route, the sacred bull is walked slowly to the centre of the manyatta. After being swiftly suffocated, it is butchered and roasted before each junior elder receives the ceremonial mouthful that will mark his metamorphosis into seniority. The time of the warrior is over; the time of wisdom has begun.