While on the one hand therapists can count on a number of codified and standardized diagnostic procedures, on the other hand it is hard to believe that in their daily work therapists slavishly follow these standardized procedures. In a clinical assessment, the diagnosis seems to be the outcome of a naïve and fuzzy process that is strongly influenced by personal training, by, theoretical models, and by one's masters as well as the experience gained in the field. What happens inside the no man's land of the clinical encounter? Can we identify some landmarks in these "amoeboid" exploratory moves? This paper addresses diagnosis not only as a noun or name ("diagnosis"), but also as a verb ("diagnosing"), arguing that a diagnostic space opens up thanks to an oscillatory state of mind that emerges at the intersection of different ways of looking "through" the symptom.