In this lecture, Xavier Rubert de Ventós reflects on the mechanisms of knowledge and sets out the following maxims: all generalisations are false; the maximum is not always the optimal; the more we know, the more we realise our failings; we often make the greatest findings when we are not looking for them, serendipitously. Likewise, he emphasises the need for knowledge to be harmonious and delicate, to adapt to its surroundings and to relate to memories and recollections.