Thoreau Celebrates the "Philosophia Botanica".

It is surprising how few readers of Thoreau go far enough afield to meet the man we find here, delighted with his botany manual, eagerly memorizing the Latin scientific names for plants, poring over illustrations for clues.  He was asked to collect scientific samples for Louis Agassiz's laboratory at Harvard. He even wrote a scientific paper that continues to be consulted today.

'I have learned in a shorter time and more accurately the meaning of the scientific terms used in botany from a few plates of figures at the end of the "Philosophia Botanica," with the names annexed, than a volume of explanations or glossaries could teach. And, that the alternate pages to the plates may not be left blank, he has given on them very concise and important instruction to students of botany. This lawgiver of science, this systematizer, this methodist, carries his system into his studies in the field. On one of these little pages he gives some instruction concerning herbatio, or what the French called herborisations, — we say botanizing. Into this he introduces law and order and system, and describes with the greatest economy of words what some would have required a small volume to tell, all on a small page; tells what dress you shall wear, what instruments you shall carry, what season and hour you shall observe, — viz. "from the leafing of the trees, Sirius excepted, to the fall of the leaf, twice a week in summer, once in spring, from seven in the morning till seven at night," — when you shall dine and take your rest, etc., in a crowd or dispersed, etc., how far you shall go, — two miles and a half at most, — what you shall collect and what kind of observations make, etc., etc.'