It is not strange that the watchful mother begins to be anxious, for she hears nothing from her son about her "project" of medicine. She writes him that she detects in his letters "a certain sadness and discontent." "How is it," she says, "that you look forward only with distaste to the practice of medicine? Have you reflected seriously before setting aside this profession? Indeed, we cannot consent to such a step; you would lose ground in our opinion, in that of your family, and in that of the public you would pass for an inconsiderate, fickle young fellow, and the slightest stain on your reputation would be a mortal blow to us.... Of course you will not gather roses without thorns. Life consists of pains and pleasures everywhere. To do all the good you can to your fellow-beings, to have a pure conscience, to gain an honorable livelihood, to procure for yourself by work a little ease, to make those around you happy, that is true happiness; all the rest but mere accessories and chimeras." And then the good Swiss minister adds, thus to quiet his son's restless nature, "If it be absolutely essential to your happiness that you should break the ice of the two poles in order to find the hairs of a mammoth, ... at least wait till your trunk is packed and your passports are signed before you talk with us about it. Begin by reaching your first aim, a physician's and surgeon's diploma.... My own philosophy is to fulfil my duties in my sphere, and even that gives me more than I can do." Fortunately Louis Agassiz did not possess the kind of philosophy that brings content in a small parish on a Swiss lake; his sphere was to be the world, and two continents were to be proud of him. In 1817, the King of Bavaria had sent two naturalists, M. Martius and M. Spix, on an exploring expedition to Brazil. They returned in four years, laden with treasures. M. Martius issued colored illustrations of all the unknown plants he had collected, and M. Spix several volumes on the monkeys, birds, and reptiles of Brazil. He had intended to give a complete natural history of Brazil, but died before his work was finished. Martius asked Agassiz to continue the work of Spix, in the line of fishes.