This essay presents some reconsiderations on Lachmann’s method applied to the concrete experience of the critical edition of humanistic texts. The apparent obviousness of a bipartite stemma is illusory, if tested outside the data obtained from the collation. The existence of an original often in motion; the notable diffusion of the phenomenon of the so-called ‘contamination’; the dispersion of the tradition; the impossibility of talking about a mechanical transmission of texts; the partiality of the sight of the modern publisher, compelled by the necessity to reconstruct the textual events starting from the observation point represented by the base text: the awareness of all these limits is the real strength of the philologist, who is called not only to rebuild texts, but even to embrace the old dictum nothing in excess.