In 1878 the 26 year-old Jacobus Henricus van't Hoff, who would receive the first Nobel Prize in Chemistry in 1901, was installed as the first Professor of Chemistry, Mineralogy, and Geology in the new University of Amsterdam. For the occasion he delivered an inaugural lecture entitled "Imagination in Science" [see translation by G. F. Springer, Springer-Verlag, 1967 from which the following extracts are adapted]. He began the address with a counter-example, quoting Hermann Kolbe who had shown such short-sightedness and intemperance in criticizing van't Hoff's most memorable work, first published when van't Hoff was 22; and Kolbe, 56. Kolbe was accustomed to using the journal he edited (Journal für praktische Chemie) as a bully pulpit for keeping chemists on the intellectual straight and narrow.

Kolbe wrote in Journal für praktische Chemie, 15, 473 ff.:

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I have recently published an article in Journal für praktische Chemie (14, 288 ff.) giving as one of the reasons for the contemporary decline of chemical research in Germany the lack of well-rounded as well as thorough chemical education. Many of our chemistry professors labor with this problem to the great disadvantage of our science. As a consequence of this, there is an overgrowth of the weed of the seemingly learned and ingenious but in reality trivial and stupefying natural philosophy. This natural philosophy, which had been put aside by exact science, is at present being dragged out by pseudoscientists from the junk-room which harbors such failings of the human mind, and is dressed up in modern fashion and rouged freshly like a whore whom one tries to smuggle into good society where she does not belong.

Whoever considers this apprehension to be exaggerated should read, if he can manage it, the recently published pamphlet, "The arrangement of atoms in space", by Messrs. van't Hoff and Herrmann, which teems with fantastic trifles. I would ignore this paper as so many others if it were not for a renowned chemist who protected this nonsense and recommended it warmly as meritorious accomplishment.

A J. H. van't Hoff who is employed at the Veterinary School in Utrecht appears to find exact chemical research not to his taste. He deems it more convenient to mount Pegasus (evidently loaned from the Veterinary School) and to proclaim in his "La chimie dans l'espace" how, to him on the chemical Parnassus which he ascended in his daring flight, the atoms appeared to be arranged in the Universe.

[After castigating Dr. Herrmann, the translator, Prof. Wislicenus, who encouraged the translation and wrote the preface (and who would succeed Kolbe in the chemistry chair at Leipzig), and the publisher, Kolbe continues:]

It is completely impossible to criticize this booklet in any detail because the fancy trifles in it are totally devoid of any factual reality and are completely incomprehensible to any clear-minded researcher. But in order to get some idea what notions the authors might have had, it suffices to read the following two sentences. The brochure begins with the words: "The modern chemical theory has two weak points. It says nothing either about the relative position or the motion of the atoms within the molecule." The other sentence, on top of page 35 of the brochure, reads: "In the asymmetrical carbon atom we have a medium which is characterized by the screwlike arrangement (sic!) of its smallest particles, the atoms!?" In order to avoid the reproach that it is not permitted to quote sentences out of context, I refer to the pamphlet itself. Everyone will convince himself that these sentences read in context are just as baroque and incomprehensible as by themselves.

It is characteristic of today's uncritical and criticism-hating time, that two virtually unknown chemists, the one from a veterinary school, the other from an agricultural institute, judge the most profound problems of chemistry which probably will never be answered. They judge these most important problems, especially the question as to the spatial orientation of the atoms, with a cock-sureness and insolence which can only astound a true student of natural science.

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Obviously Kolbe was silly to be so intemperate and spiteful. He was also short-sighted, and he guessed wrong. We can easily appreciate that in the court of history he got what was coming to him.

The challenge is properly to respect the indispensable contributions the attitude he was championing had made to the development of chemistry. It was by sticking close to careful experimental observations that chemistry had gotten where it was (and is). Kolbe was trying to keep science on a productive, intellectually justifiable path.

What Kolbe missed was that van't Hoff's observations, while speculative, were indeed based on many published experimental facts. Kolbe's mind had closed, and he couldn't imagine that it might be possible to infer structure from indirect experimental evidence. He was far from alone in this espousing point of view (cf. Lieben).

In an independent controversy in 1877, 35-year-old Albert Ladenburg, like van't Hoff a student of Kekulé, wrote,

Van't Hoff is dragging something into the formulas which I together with most chemists expressly exclude. I refer to arrangement in space. What I understand in a formula takes account of the composition, molecular weight, and mode of union of the atoms. [i.e. Composition and Constitution only]

The scientists I know and respect have, like me, swallowed the doctrine that one can't measure things that quantum mechanics says we can't measure. The customary corollary is that it is improper to think about such things.

Another example of forbidden territory is thinking about what happens inside a Black Hole or before the Big Bang. The New York Times, Nov. 9, 2002, described how the French Bogdanov twins are held up to scorn (probably properly) for speculating about Before the Big Bang: "'This says something profound about what happens to theoretical physics in the absence of the discipline of experiment,' Dr. Wilczek said."

Are these points of view all that different from Kolbe's? Are they now right? I mean these as serious questions. The answers aren't all that clear to me.

In "The First Three Minutes" (1977), when discussing the discovery of the microwave background radiation that proved to be the echo of the Big Bang, Stephen Weinberg, a Nobel Prize winning theoretical physicist, wrote:

...our mistake is not that we take our theories too seriously, but that we do not take them seriously enough.

...Even worse, there often seems to be a general agreement that certain phenomena are just not fit subjects for respectable theoretical and experimental effort.