It was the conductor Wilhelm Furtwängler who first gave Gottlob Frick the nickname "Der schwärzeste Bass". This accolade has been picked up time and again, gone through various manifestations, and become a sort of trademark of the German bass Gottlob Frick. That said, the attribute "black" is often applied to define the vocal range of a basso profundo's ability to produce sonorous deep notes. However, the definition of "black bass" means far more than that: it applies primarily to the deep, dark timbre, the rich and sonorous sound and the lasting flexibility of the voice even in the deep registers, paired with strength, momentum, natural resonance and abundant expression in the entire vocal range. "If you have ever heard the timbre of Gottlob Frick's voice, you will never forget it," as the German singing expert Jürgen Kesting accurately observed in his standard reference work "Die großen Sänger". Gottlob Frick is seen rightly therefore as the incarnation of the black bass. He is a German bass who, thanks to the many sound recordings he left us documenting his sonorous, unusually beautiful and fluently melodic singing, enjoys a popularity to this day that is probably unparalleled in this vocal register. One of the reasons the internationally renowned critic John B. Steane advanced to justify his inclusion of Gottlob Frick in his list of 100 most important singers in "Opera Now" is encapsulated in this fitting characterisation: "When it comes to the Wagnerian basso profundo, the only name in recent times that matters" – by which he means the 1940s to 1980s – "is that of Gottlob Frick: a tower of strength in the strongest ensemble and one of the greatest basses of all time. His voice is steady despite its powerful capacity, supple and splendid. Frick's two-and-a-half-octave bass is remarkably well trained and remains constant through its entire spectrum. He has a strong sense of rhythm and he can sing both legato and staccato in exemplary manner, without depriving his listeners of that rich timbre of his."