Possible Clues:

• Composer open to receive criticism upfront
• He shared the 1925 Nobel Prize in Physics with Hertz
• César —, Liège-born composer
• Stamp carrying head of commemorated composer
• Composer is candid, we hear
• Composer's candid about origin of composition
• Belgian-born French composer, d. 1890
• César —, Belgian composer
• César ___ , Belgian-born French composer, d. 1890
• James --, 1882-1964, US physicist born in Germany