Sitting on the promontory of Sasakwa Hill, overlooking the boundless sun-washed Serengeti, I watched the shadow of a cloud move over the landscape. It was a dark shadow shaped like an arrow with a very long shaft. At first I didn't take much notice. I was more interested in a late afternoon nap.
I closed my eyes. "Clouds aren't shaped like arrows," I thought sleepily. "They don't have skinny tails that stretch for 10 miles. And there isn't a cloud in sight."
I opened my eyes and studied the shadow again, this time through a telescope. Through the haze of dust sent up by a hundred thousand (or two hundred thousand, or maybe a million) hooves, I saw that this was in fact a mass of wildebeest, the rear guard of nearly 2 million grazing animals that annually pass within view of Grumeti Reserves, possibly the world's most luxurious eco-tourism resort.