Brian Wilson’s 1966 masterpiece is now considered a crowning achievement of music. The album’s reputation grew over time.

The Beach Boys leader, whose death was announced on Wednesday, was a brilliant writer, arranger and producer whose ambitions propelled his band — and contemporaries like the Beatles — into the future.

As his songs for the Beach Boys began to broaden beyond the hot-rod and surf themes, “In My Room” was a sign of things to come. With each line in the first verse adding an additional harmony atop, ...