Apparent as is the advance of the “Eroica” over its predecessor, the difference between these and the two later sonatas—­the “Norse” and the “Keltic”—­is even more marked.  The first of these, the “Norse” sonata (op. 57) appeared five years after the publication of the “Eroica.”  In the interval he had put forth the “Woodland Sketches,” the “Sea Pieces,” and the songs of op. 56 and op. 58; and he had, evidently, examined deeply into the resources and potentialities of his art.  He had hitherto done nothing quite like these two later sonatas; they are based upon larger and more intricate plans than their predecessors, are more determined and confident in their expression of personality, riper in style and far freer in form:  they are, in fact, MacDowell at his most salient and distinguished.  He has placed these lines of his own on the first page of the score of the “Norse” (which is dedicated to Grieg): 

  “Night had fallen on a day of deeds. 
  The great rafters in the red-ribbed hall
  Flashed crimson in the fitful flame
  Of smouldering logs;
  And from the stealthy shadows
  That crept ’round Harald’s throne
  Rang out a Skald’s strong voice
  With tales of battles won: 
  Of Gudrun’s love
  And Sigurd, Siegmund’s son.”

Here, evidently, is a subject after his own heart, presenting such opportunities as he is at his happiest in improving—­and he has improved them magnificently.  The spaciousness of the plan, the boldness of the drawing, the fulness and intensity of the colour scheme, engage one’s attention at the start.  He has indulged almost to its extreme limits his predilection for extended chord formations and for phrases of heroic span—­as in, for example, almost the whole of the first movement.  The pervading quality of the musical thought is of a resistless and passionate virility.  It is steeped in the barbaric and splendid atmosphere of the sagas.  There are pages of epical breadth and power, passages of elemental vigour and ferocity—­passages, again, of an exquisite tenderness and poignancy.  Of the three movements which the work comprises, the first makes the most lasting impression, although the second (the slow movement) has a haunting subject, which is recalled episodically in the final movement in a passage of unforgettable beauty and character.

With the publication, in 1901, of the “Keltic” sonata (his fourth, op. 59),[15] MacDowell achieved a conclusive demonstration of his capacity as a creative musician of unquestionable importance.  Not before had he given so convincing an earnest of the larger aspect of his genius:  neither in the three earlier sonatas, in the “Sea Pieces,” nor in the “Indian” suite, had he attained an equal magnitude, an equal scope and significance.  Nowhere else in his work are the distinguishing traits of his genius so strikingly disclosed—­the breadth and reach of imagination, the magnetic vitality, the richness and fervour, the conquering poetic charm.