It is difficult for us to realise the condition of natural science as it existed in Germany, at least in the first twenty years of this century. Magnus was born in 1802; I myself nineteen years later; but when I go back to my earliest recollections, when I began to study physics out of the school-books in my father’s possession, who was himself taught in the Cauer Institute, I still see before me the dark image of a series of ideas which seems now like the alchemy of the middle ages. Of Lavoisier’s and of Humphry Davy’s revolutionising discoveries, not much had got into the school-books. Although oxygen was already known, yet phlogiston, the fire element, played also its part. Chlorine was still oxygenated hydrochloric acid; potash and lime were still elements. Invertebrate animals were divided into insects and reptiles; and in botany we still counted stamens. It is strange to see how late and with what hesitation Germans applied themselves to the study of natural science in this century, whilst they had taken so prominent a part in its earlier development. I need only name Copernicus, Kepler, Leibnitz, and Stahl. For we may indeed boast of our eager, fearless and unselfish love of truth, which flinches before no authority, and is stopped by no pretence; shuns no sacrifice and no labour, and is very modest in its claims on worldly success. But even on this account she ever impels us first of all to pursue the questions of principle to their ultimate sources, and to trouble ourselves but little about what has no connection with fundamental principles, and especially about practical consequences and about useful applications. To this must be added another reason, namely, that the independent mental development of the last three hundred years, began under political conditions which caused the chief weight to fall on theological studies. Germany has liberated Europe from the tyranny of the ancient church; but she has also paid a much dearer price for this freedom than other nations. After the religious wars, she remained devastated, impoverished, politically shattered, her boundaries spoiled, and arrogantly handed over defenceless to her neighbours. To deduce consequences from the new moral views, to prove them scientifically, to work them out in all regions of intellectual life, for all this there was no time during the storm of war; each man had to hold to his own party, every incipient change of opinion was looked upon as treachery, and excited bitter wrath. Owing to the Reformation, intellectual life had lost its old stability and cohesion; everything appeared in a new light, and new questions arose. The German mind could not be quieted with outward uniformity; when it was not convinced and satisfied, it did not allow its doubt to remain silent. Thus it was theology, and next to it classical philology and philosophy, which, partly as scientific aids of theology, partly for what they could do for the solution of the