The concept of 'Mother Sauces' is the foundation of classical French cuisine. In the early 20th century, legendary chef Auguste Escoffier codified the five basic sauces from which hundreds of 'daughter' sauces can be made. These are: Béchamel (white roux and milk), Velouté (white roux and white stock), Espagnole (brown roux and brown stock), Sauce Tomate (tomatoes and roux), and Hollandaise (egg yolks and liquid butter). The ability to master these sauces is considered the true test of a professional chef. For instance, by adding cheese to a Béchamel, you create a Mornay sauce. Escoffier's system revolutionized professional kitchens by providing a standardized framework for culinary education and kitchen organization.