This digression upon the Naturalists was needed partly to illustrate the nature of the attempted revival of the art of painting at this epoch, and partly to introduce two notable masters of the Bolognese school.  Lionello Spada, a street-arab of Bologna, found his way into the studio of the Caracci, where he made himself a favorite by roguish ways and ready wit.  He afterwards joined Caravaggio, and, when he reappeared in Lombardy, he had formed a manner of his own, more resplendent in color and more naturalistic than that of the Caracci, but with less of realism than his Roman teacher’s.  If I could afford space for anecdotical details, the romance of Spada’s life would furnish much entertaining material.  But I must press on toward Guercino, who represents in a more famous personality this blending of the Bolognese and Naturalistic styles.  Giovanni Francesco Barbieri got his nickname of Il Guercino, or the ‘Squintling,’ from an accident which distorted his right eye in babyhood.  Born of poor parents, he was apprenticed to indifferent painters in Bologna at an early age, his father agreeing to pay for the boy’s education by a load of grain and a vat of grapes delivered yearly.  Thus Guercino owed far less to academical studies than to his own genius.  Being Lodovico Caracci’s junior by thirty-five years, and Annibale’s by thirty, he had ample opportunities for studying the products of their school in Bologna, without joining the Academy.  A generation lay between him and the first Eclectics.  Nearly the same space of time separated Guercino from the founder of the Naturalists, and it was universally admitted in his lifetime that he owed to Caravaggio in coloring no less than he derived from the Caracci in sobriety and dignity of conception.  These qualities of divergent schools Guercino combined in a manner marked by salient individuality.  As a colorist, he approached the Tenebrosi—­those lovers of surcharged shadows and darkened hues, whose gloom culminated in Ribera.  But we note a fat and buttery impasto in Guercino, which distinguishes his work from the drier and more meager manner of the Roman-Neapolitan painters.  It is something characteristic of Bologna, a richness which we might flippantly compare to sausage, or a Flemish smoothness, indicating Calvaert’s influence.  More than this, Guercino possessed a harmony of tones peculiar to himself, and strongly contrasted with Guido’s silver-gray gradations.  Guido’s coloring, at its best, often reminds one of olive branches set against a blue sea and pale horizon in faintly amber morning light.  The empurpled indigoes, relieved by smouldering Venetian red, which Guercino loved, suggest thunder-clouds, dispersed, rolling away through dun subdued glare of sunset reflected upward from the west.  And this scheme of color, vivid but heavy, luminous but sullen, corresponded to what contemporaries called the Terribilita of Guercino’s conception.  Terribleness was a word which came into vogue to describe Michelangelo’s grand manner.  It implied audacity of imagination, dashing draughtsmanship, colossal scale, something demonic and decisive in execution.[233] The terrible takes in Guercino’s work far lower flights than in the Sistine Chapel.  With Michelangelo it soared like an eagle; with Guercino it flitted like a bat.  His brawny saints are ponderous, not awe-inspiring.