ABSTRACT
When the master had finished the first part of his book and had written down his thoughts concerning the exposition of the theoretical branch of philosophy, he then set about to carry out the promise made in his prologue, to speak of the two other branches in the body of philosophy, that is, the practical and the logical, which teach man what he must do and what he must not do, and why he must do some things and not others. 2. But he will present these two branches together, because they are so intertwined that they can hardly be separated. This is the second part, which will be of precious stones, which are the virtues, the words and teachings of wise men, each one of which is valuable for the life of men, for beauty, for delight and for virtue, for no stone has value if it is not for these three things. 3. This teaching will be about the four active virtues, the first of which is prudence, represented by the ruby, which lights up the night and shines brighter than all other precious stones. The second is temperance, represented by the sapphire, which is of a celestial color; and it is the most filled with grace of all the precious stones in the world. The third is courage, represented by the diamond, which is so strong that it breaks and pierces all stones and metals, for which reason there is nothing that it fears. The fourth virtue is justice, represented by the emerald, which is the greenest and most beautiful thing human eyes can behold. 4. These are the most precious stones of the treasure, which is also filled with other stones, each of which has some worth, as the attentive reader will see and learn through the words written by Master Brunetto Latini in this book. But first of all he wishes to use Aristotle's book as the foundation for his own; he will translate it from Latin into Romance, and he will place it at the beginning of the second part of his book, in this manner.
