This book by Messrs Voisin and Lecomte comes at the right moment. It is a synthesis of M. Voisin's important study, Grass Productivity. This manual presents the chief ideas of two specialists. Since they are also excellent practitioners, they have applied these ideas before recommending them. Their evocative picture of 'the meeting of cow and grass' poses the true problem of the management of grazed grass. For the farmer, the production of meat and milk is an act of industrial conversion. The 'machine' is the animal that converts raw vegetable matter into finished food products which are rich in calories and easy to assimilate. This 'machine' is complex because it is a living being; it can be improved--within limits. But its yield depends basically on the quality of the raw materials offered to it for conversion. I hope that their words will be heard and followed. From the Introduction]