Take a good slice of ham fat, and chop very fine with it a piece of onion, a piece of celery, and some parsley. 

Then put this into a frying-pan and cook until the grease is colored. (If desired, add a small lump of butter.) 

When well colored add two tablespoons of tomato
paste dissolved in a little hot water. Boil all together for fifteen minutes.

If no tomato paste is available make the tomato sauce as follows:

Chop up fine one-quarter of an onion, a piece of celery the length of a finger, two or three basil-leaves, and a small bunch of parsley.
Slice seven or eight tomatoes (fresh or canned), add salt and pepper, and put all on together to cook in four tablespoons of good olive-oil.
Stir occasionally, and when it becomes as thick as cream, strain, and add the pasta.