To trace nature from the trivial differences which may distinguish between two kindred mosses--differences scarcely to be detected by the practised eye of the botanist--upwards to the grand grouping of organized matter, into kingdoms containing myriads of such species,--to define accurately major and minor divisions, and assign to each division, and each individual, its appropriate place in an enduring system, is a task, in all probability, far beyond the mental powers of any single individual, especially when we consider the interesting facts and fresh objects which are daily added to our store in such number as must convince the student that as yet he scarcely possesses a knowledge of one hundredth part of nature's works;[15] but, to pencil a dim and dubious outline,--to suggest whether nature has not aimed at such and such conclusions,--whether she has not chosen such and such paths, without making the slightest attempt to bend or turn her aside from her course where it does not precisely coincide with his own artificial schemes, may be fairly claimed as the privilege of any of her students, and ought to be freely granted to him by his fellow-labourers. [15] In Britain we labour under another difficulty in this respect, a difficulty which has proved beyond measure mortifying during the progress of the present essay,--the want of a national museum.--A private individual cannot be expected to sacrifice all his time and money in procuring, preparing, and arranging, a tolerably perfect collection; a writer on natural history is, therefore, compelled to travel round to two or three hundred private collections, and solicit leave to make his memoranda. Few men of taste can regret the purchase of the ancient works of art now open to the public at the British Museum; but the immense sums of public money granted to that institution should insure the naturalist a similar treat with the artist. A collection of vertebrate and annulose animals should be immediately formed, arranged, and named after Cuvier, Latreille, or the most approved authority of the day. Among the insecta, I have no doubt a tolerably perfect--certainly, a very useful--collection might with little trouble be made from the specimens already in the Museum.