My dear Hooker,

Better late than never; and where there is ample reason for lateness, there can be none for complaint. Many thanks for your letter de convergentibus &c.—¹ How much outside the botanical circles,—or, at any rate the great circle,—not even to have heard that you had been beyond seas again!² Was there ever a botanist who had seen so much of the earth & its vestments?³

How vastly I should have enjoyed the run over Syria with you! And yet if I had chanced to be away from England those eight weeks, inconveniences to myself & others would have been so incurred, that might hardly have been removed in as many years. I seem always called on to give time & thought to things no wise botanical, while wishing to give them to matters that are botanical, or connected with botany.⁴

I can hardly conceive you & Mr. Bentham employed more serviceably than on a ‘Genera Plantarum’.⁵ So many qualifications & advantages concentrate in you two, towards such an undertaking, that the accomplishment of your task ought to date as a new formation in the series of botanical strata—& doubtless will do so.— Can a list of species under each genus be compassed, if only single names?⁶

You have not yet grasped the whole idea of convergence, as I conceive of it whether rightly or erroneously.⁷ No wonder. If Darwin had sought to explain his notions of divergence & selection in compass of a letter sheet, he might have got further or fuller than I could do with its (presumed) counterpoise, & yet done it most imperfectly.

Darwin watches minutesimal variations; & he supposes that these may & do accumulate into any extent of diversity in long time.— I suspect that we should all have said, that is pure fancy or pure absurdity, if geology had not shown the fact, that enormous differences do exist between the present & the past, & must have come about somehow.⁸

I watch minutesimal variations also; & I suppose that these may & do accumulate into any degree of similarity in long time. But, seeing that we know not the future, and cannot compare the present therewith, we lack corroboration. And we (i.e. you &c.) do think convergence to such a degree mere fancy or absurdity.

You & Darwin seem to me at present something like an Astronomer endeavouring to account for the planetary system by a centrifugal force alone, without taking into account a centripetal force, or recognising it only as occasional, anomalous, trifling.⁹ Darwin’s idea that similitudes must be always inherited from some predecessor, common ancestor of all that so resemble, if pushed to its logical consequences, would concentrate all organic characters in the dozen (or single) original types;—and that surely is a real as well as logical absurdity?¹⁰

Observe,—every the smallest possible change in a plant, which to that extent renders it more like another plant, (whether that other plant be the nearest, or the most remote otherwise) is a step in convergence. Advergence would perhaps be a better term. Can you point out divergences in any plants, which are certainly not advergences towards some other plants?

You will be ready to cry, ‘Hold enough’. And I will not inflict on you a criticism of the various ideas in your letter;—some of which indeed I quite admit the force of; though I think that the arguments against ad/convergence are not proof against reply.—

The Indian specimens you kindly sent some time ago are still kept apart, awaiting some other introductions into my herbarium, before trying how closely I can concur with your labels of European identity.¹¹ Unlike you, I have to go through all the mechanical processes, such as washing over with poison, glueing to paper, & so forth,—sadly time-consuming.¹²

Writing with back to the fire, I still have to keep rubbing fingers, or the pen would fall from their cold benumbed trembling guidance—

Glad to have so favorable an account of your Father—¹³

Ever faith^ly | Hewett C. Watson

Dr J. D. Hooker