"But to speak the truth the poets and writers of history are the best doctors of this knowledge,[56] where we may find painted forth with great life and dissected, how affections are kindled and excited, and how pacified and restrained, and how again contained from act and further degree; how they disclose themselves, though repressed and concealed; how they work; how they vary; how they are enwrapped one within another; how they fight and encounter one with another; and many more particulars of this kind; amongst which this last is of special use in moral and civil matters; how, I say, to set affection against affection, and to use the aid of one to master another; like hunters and fowlers who use to hunt beast with beast, and catch bird with bird, which otherwise perhaps without their aid man of himself could not so easily contrive; upon which foundation is erected that excellent and general use in civil government of reward and punishment, whereon commonwealths lean; seeing these predominant affections of fear and hope suppress and bridle all the rest. For as in the government of States it is sometimes necessary to bridle one faction with another, so is it in the internal government of the mind." In his "Distributio Operis" Bacon thus describes the missing fourth part of his "Instauratio Magna":-- "Of these the first is to set forth examples of inquiry and invention[57] according to my method exhibited by anticipation in some particular subjects; choosing such subjects as are at once the most noble in themselves among those under enquiry, and most different one from another, that there may be an example in every kind. I do not speak of these precepts and rules by way of illustration (for of these I have given plenty in the second part of the work); but I mean actual types and models, by which the entire process of the mind and the whole fabric and order of invention from the beginning to the end in certain subjects, and those various and remarkable, should be set as it were before the eyes. For I remember that in the mathematics it is easy to follow the demonstration when you have a machine beside you, whereas, without that help, all appears involved and more subtle than it really is. To examples of this kind--being, in fact, nothing more than an application of the second part in detail and at large--the fourth part of the work is devoted."