An ancient art of divination also known as tiromancy, from the Greek tyros meaning cheese.
The basic idea is that there is something to be gleaned from the observation of cheese, especially during coagulation. The shapes, smells, colours, et cetera provide for the diviner some kind of special knowledge. Especially useful is cheese's tendancy to change over time - perhaps the future will become clearer if we just wait a few days? The cheese will speak, it just needs a moment.
Very much along similar lines to seeing the face of Jesus in a petrol stain on the floor of a mechanical workshop (to use an overly specific but charmingly local example), tyromancy began when someone noticed that, occasionally, the varied shapes produced as cheese did the cheese thing actually looked like something. From the whorls that collect and dissipate as cheese is made, to the shapes of the mould that grows thereon after the passing of a little time, to the strange face-like shapes that a perfectly ordinary block of cheese shrinks into; these are all the voices of nature speaking of things beyond human ken, yet translatable by the initiated.
One of the earliest references in literature to this practice comes from 1660. In Urquhart's translation of François Rabelais's Gargantua & Pantagruel we find:
By Tyromancy, whereof we make some Proof in a great Brehemont Cheese, which I here keep by me.
This writer could not determine from sources whether or not this form of divination only works for Brehemont, or whether, at a pinch, any cheese will do.
Sources:
The Complete Illustrated Book of Divination Walter Gibson 1973 Doubleday
Various websites, esp. http://www.webspinning.com.au/home/lambertj/public_html/t.man.html
Behold the power of cheese...