The reason for the writing of this book was, in the author's words, that 'There is a wide-spread belief that guinea-pigs are, of all animals, the most stupid. Yet for the most part it may be mere gossip and hearsay. Where is the man who has cared to investigate the matter seriously and report whether the popular belief is truth or, as in many another instance, only vulgar error? I have looked for him in vain. Indeed, it is because of this that I have constituted and delegated myself envoy to report upon the matter.'