who said the greatest thing is to love and be loved in return
Eden Ahbez.
Nature Boy
. The song was written in 1947 by eden ahbez and is partly autobiographical. It is a tribute to ahbez's mentor Bill Pester, who had originally introduced him to Naturmensch and Lebensreform philosophies, which ahbez practiced. When Cole was performing in 1947 at the Lincoln Theater, ahbez wanted to present the song to him, but was ignored. He left the copy with Cole's valet, and from him the singer came to know of "Nature Boy". After receiving appreciation for his performance of the song, Cole wanted to record it but needed consent from the writer. Eventually, he tracked down ahbez. 

The recording took place on August 22, 1947, and featured an orchestra conducted by Frank De Vol—the in-house arranger of Capitol Records. He used strings and flute as instrumentation in the song, to capture the "enchanting" vibe of the track. The lyrics are a self-portrait of ahbez and his life. The final line—"The greatest thing you'll ever learn, Is just to love and be loved in return"—is considered a 
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Nature Boy [SEP] Introduction
"Nature Boy" is a song first recorded by American jazz singer Nat King Cole. It was released on March 29, 1948, as a single by Capitol Records, and later appeared on the album, "The Nat King Cole Story". The song was written in 1947 by eden ahbez and is partly autobiographical. It is a tribute to ahbez's mentor Bill Pester, who had originally introduced him to Naturmensch and Lebensreform philosophies, which ahbez practiced. When Cole was performing in 1947 at the Lincoln Theater, ahbez wanted to present the song to him, but was ignored. He left the copy with Cole's valet, and from him the singer came to know of "Nature Boy".