If using fresh truffles, clean them with a stiff brush, rinse them briefly, and pat thoroughly dry.  It using preserved truffles, drain them and pat them dry.  Do not discard the liquid; save it to add to a roast or meat sauce.

Grate the truffles to a very fine-grain consistency, using the smallest holes of a flat-sited grater.  If you have a good mortar and pestle, chop them up and grind them to a pulp in the mortar.

Put the truffles into a small earthenware saucepan.  If you do not have earthenware, use enameled cast iron.  Add the olive oil, trickling it in a little at a time, and stirring thoroughly.

Turn on the heat to low, and add the garlic and the chopped anchovy.  Stir with a wooden spoon for about 10 minutes, mashing the anchovy until it is almost completely dissolved into a paste.  Keep the heat low, and do not let the oil bubble.  If the oil becomes too hot, move the pay away from the heat for a few moments.  Add salt to taste, stir once or twice, and remove from heat.

Cook the pasta in 3 to 4 quarts salted boiling water.  Bear in mind that thin spaghetti cooks rather quickly.  As soone as it is cooked al dente, tender but firm to the bite, drain it quickly, and transfer to a war bowl.

Remove the garlic from the truffle sauce, and pour all the contents on the pan over the spaghetti.  Toss thoroughly, and serve at once.