Frederick Soddy was in his 75th year when he lectured at Lindau for the first time, almost 30 years after having received the Nobel Prize in Chemistry. In the meantime, he had acquired a reputation as a rather curious fellow, with a series of publications on futuristic societal economic questions and with a published poem stating a mathematical result of his. But for the lecture at Lindau, he returned to his profession as a chemist and gave a long and intricate talk on the history of isotopes. Actually, the talk he planned was too long, as we can hear him comment after about 60 minutes (!) and as can be seen from the version printed in a special publication of the journal Naturwissenschaftliche Rundschau from 1981. From the publication it can be seen that the full talk, consisting of two parts, was later given at the Max-Planck-Institute in Mainz, which, according to Soddy, was “the only institute in the world fully dedicated to the study of isotopes”. Soddy nicely starts his talk by telling a story in broken German, but for the core of the talk he apologizes to the audience and switches to his mother tongue. Thus his talk becomes the first one recorded at Lindau in English and is an early signal of the internationalization of both the speakers and the audiences at the Lindau meetings. But there is also another reason to look upon his talk as a real historic event: In the audience was, among others, Otto Hahn, Georg de Hevesy and Irène Joliot-Curie. All three of them were specialists on the subject of radiochemistry, a subject that was almost impossible to understand before the concept of isotopes. This is so because radioactive disintegrations typically lead to a whole series of radioactive products. These were looked upon as new elements to be inserted in the periodic table, but were in reality only isotopes of known elements. Since two isotopes of the same element have the same chemical properties, they cannot be separated by chemical means, only by their mass. When this was realized around 1913, all the pieces of the puzzle fell into place. Interestingly, Soddy points out that two American chemists, Mc Coy and Ross, had the main isotope idea already in 1907. In an unpublished “Introduction” to his lecture he mentions that he would have been happy to share his Nobel Prize with them!