This teaching of truth as a habit will be the chief work the master has to do; and it will enter into all parts of education. First, you must accustom the children to close accuracy of statement; this both as a principle of honor, and as an accomplishment of language, making them try always who shall speak truest, both as regards the fact he has to relate or express (not concealing or exaggerating), and as regards the precision of the words he expresses it in, thus making truth (which, indeed, it is) the test of perfect language, and giving the intensity of a moral purpose to the study and art of words: then carrying this accuracy into all habits of thought and observation also, so as always to _think_ of things as they truly are, and to see them as they truly are, as far as in us rests. And it does rest much in our power, for all false thoughts and seeings come mainly of our thinking of what we have no business with, and looking for things we want to see, instead of things that ought to be seen. 99. "Do not talk but of what you know; do not think but of what you have materials to think justly upon; and do not look for things only that you like, when there are others to be seen"--this is the lesson to be taught to our youth, and inbred in them; and that mainly by our own example and continence. Never teach a child anything of which you are not yourself sure; and, above all, if you feel anxious to force anything into its mind in tender years, that the virtue of youth and early association may fasten it there, be sure it is no lie which you thus sanctify. There is always more to be taught of absolute, incontrovertible knowledge, open to its capacity, than any child can learn; there is no need to teach it anything doubtful. Better that it should be ignorant of a thousand truths, than have consecrated in its heart a single lie. 100. And for this, as well as for many other reasons, the principal subjects of education, after history, ought to be natural science and mathematics; but with respect to these studies, your schools will require to be divided into three groups: one for children who will probably have to live in cities, one for those who will live in the country, and one for those who will live at sea; the schools for these last, of course, being always placed on the coast. And for children whose life is to be in cities, the subjects of study should be, as far as their disposition will allow of it, mathematics and the arts; for children who are to live in the country, natural history of birds, insects, and plants, together with agriculture taught practically; and for children who are to be seamen, physical geography, astronomy, and the natural history of sea-fish and sea-birds.