Arturo Toscanini's supreme importance in the history of conducting is universally acknowledged. The standard of orchestral playing taken for granted in the twenty-first century owes more to him than to any other single figure; and the stylistic influence, today sometimes questioned, is still pervasive, if often unacknowledged or known only at second hand. That influence, however, is (for better or for worse) a product principally of his later years when he was in charge of the NBC Symphony Orchestra, a radio orchestra of unique stature whose recordings were disseminated worldwide.

Although Toscanini was recognised as supreme in his art far into the twentieth century, his career to some degree antedated that century's characteristic phenomenon, the peripatetic conductor. Such travellers were not unknown in his early years even amongst the finest conductors – Felix Weingartner in particular, together with Arthur Nikisch, Fritz Steinbach and other great names; but the careers of some of the very greatest were in that era fulfilled by the occupation of a relatively small number of posts that limited the number of appearances elsewhere. Just as for, say, Mahler, the progression from Hamburg and Vienna to his two New York posts was accompanied by a relative scattering of concerts across Europe, so with Toscanini the principal posts were similarly confined to two countries: Turin and Milan in Italy; the Metropolitan Opera, the New York Philharmonic and NBC Symphony Orchestras in America. During the first half of his career concert engagements elsewhere were neither numerous nor geographically adventurous.