[In memory such power is hidden].

The article demonstrates, using a concrete example, how important the testimony of a contemporary is as a source of historical research. The testimony of this kind, supplementing archival materials, is capable to refute commonly accepted concepts and to bring the researcher nearer to understanding the real development of events. Thus, the letter of our former compatriot, whose life was saved in January 1942 by virtue of penicillin, urged author on further scientific research, that resulted in reconsideration of conception of time and circumstances of organization of first deliveries of antibiotic to the USSR. Also. the explanation was given to certain facts related to the history of its development and organization of production in our country.