A man cannot be professor of zoölogy on one day and of chemistry on the next, and do good work in both. As in a concert all are musicians,-one plays one instrument, and one another, but none all in perfection.
The study of Nature is intercourse with the highest mind. You should never trifle with Nature. At her lowest her works are the works of the highest powers, the highest something in the universe, in whichever way we look at it... This is the charm of Study from Nature itself; she brings us back to absolute truth wherever we wander.
You cannot do without one specialty. You must have some base-line to measure the work and attainments of others. For a general view of the subject, study the history of the sciences. Broad knowledge of all Nature has been the possession of no naturalist except Humboldt, and general relations constituted his specialty.
