Things, qualities, actions, relations, transformations, spatial and temporal references, all that, even mind properties, are matter for thought through words. Words are our universal way of putting sense in our relation with the world, with the others and with us, our most powerful control arm. Words have meaning, but also form and beauty. Words are particles, both corpuscles and waves, of our mental substance. The words in our head are what psychologists have called the mental lexicon – the mental representations of words –, and the study of the mental lexicon and of lexical processing is therefore a central topic in psychological science.