It is entirely otherwise with the creatures of imagination, of which no one can give an explanation or an intelligible concept; they are, as it were, monograms, individual traits, though not determined through any assignable rule, constituting more a wavering sketch, as it were, which mediates between various appearances, than a determinate image, such as what painters and physiognomists say they have in their heads, and is supposed to be an incommunicable silhouette of their products or even of their critical judgments.