I have been asked to write a foreword to the next edition of the Vademecum of Clinical Bio- chemistry renamed to Differential Diagnosis by Laboratory Medicine. The Editor in-Chief, Professor Dusan Mesko, conceived the idea of the Vademecum during a very intensely, in- tellectually active period as a visiting Olga Havel Fellow from Slovak Republic at the Mayo Clinic in Rochester. It was here during his study stay that much of the conceptual planning...