Nielsen sublimated his anger and frustration over his marriage in a number of musical works, most notably between 1897 and 1904, a period which he sometimes called his "psychological" period. Fanning writes, "At this time his interest in the driving forces behind human personality crystallized in the opera "Saul and David" and the Second Symphony ("The Four Temperaments") and the cantatas and ". Carl suggested divorce in March 1905 and had considered moving to Germany for a fresh start, but despite several extended periods of separation the Nielsens remained married for the remainder of the composer's life.