Max Beckmann's opinion on this issue you find in: 'Quotes About Franz Marc', below 
Source: 1915 - 1916, 100 Aphorisms', Franz Marc (1915), p. 445-446
                                    
Franz Marc: Quotes about art
Franz Marc was German painter. Explore interesting quotes on art.1911 - 1914, The 'Savages' of Germany' (1912)
                                        
                                        Quote of Franz Marc, in exhibition-text 'Die Blaue Reiter', Gemeentemuseum the Hague, Netherlands 2010 
c. 1914/15, on the death of his close friend August Macke, who fell in the first months of World War 1. 
1915 - 1916
                                    
Source: 1915 - 1916, 100 Aphorisms', Franz Marc (1915), p. 445
                                        
                                        co-authored with Wassily Kandinsky 
1911 - 1914 
Source: Franz Marc's Manifesto for 'the Blaue Reiter' group, (1912); as quoted in Letters of the great artists – from Blake to Pollock, Richard Friedenthal, Thames and Hudson, London, 1963, p. 207
                                    
Source: 1915 - 1916, 100 Aphorisms', Franz Marc (1915), p. 445
                                        
                                        near Verdun, 1915] 
Source: 1915 - 1916, 100 Aphorisms', Franz Marc (1915), p. 446
                                    
                                        
                                        quote from Franz Marc's note in 1907, he wrote down on his return from Paris; as cited by de:Wolf-Dieter Dube, in Expressionism; Praeger Publishers, New York, 1973, p. 126 
1905 - 1910
                                    
                                        
                                        1911 - 1914 
Source: 'Blaue Reiter' (1912), p. 75–76; as quoted on Wikipedia/El Greco, in 'Postumus critical reputation'
                                    
1911 - 1914, The 'Savages' of Germany' (1912)
1911 - 1914, The 'Savages' of Germany' (1912)