The unwieldy title of Stevie Wonder's 'Journey Through 'The Secret Life of Plants'' grew out of its origins as a soundtrack to a documentary based on 'Secret Life of Plants' -- a 1973 book written by Peter Tompkins and Christopher Bird suggesting the possibility that plant life has feelings, specifically toward empathy and eroticism.

Released on October 30, 1979 via Motown's Tamla label, the project is better known now simply as the deeply earnest, strangely involving, utterly free-form home of 'Send One Your Love,' a song that went Top 4 on both the soul and pop charts. The rest of 'Secret Life' is dominated by instrumental passages -- many of them keyed by the early use of a digital sampling synthesizer. They were meant to sync up with the film, which followed a group of scientists and artists who attempted to chart these possible feelings, rather than as stand-alone items.

Still, that didn't stop the project (which arrived as the follow up to 1976's 10-times platinum blockbuster 'Songs in the Key of Life') from racing toward the top of the Billboard album list, anyway -- though sales quickly flattened. It was, of course, a move as bold as it was commercially foolhardy -- but Wonder was unbent.

"I think that we cannot allow ourselves to put boundaries on what we do musically," he told the Washington Post in 1979. "An element of surprise is always good."

Oh, the surprises tucked away inside were many, as Wonder worked to create something brand new. Call it prog soul, maybe? The results, whatever their title, amounted to a boundary-free blend of funk and disco, pop and classical, African and Eastern orchestration, ambient and R&B. Turning his back on the pre-packaged pop that he'd just recently ridden to dizzying fame, Wonder instead traces plant life from 'Earth's Creation' and 'The First Garden' -- the latter of which features a lovely duet between a birdsong and his harmonica -- through the idea of reincarnation through the different 'Seasons,' and into the revelation of these heretofore unknown plant senses.

Whether listeners ended up buying into the theory matters less than how open, how vulnerable, and ultimately how communally loving Wonder's approach is -- especially on the propulsive 'A Seed's a Star and Tree Medley.' Oh, and also how radical. Few at his level of success would risk so much, and Wonder remains proud of that risk.

Later, he described 'Journey Through 'The Secret Life of Plants'' as one of his most exciting creative moments -- saying that the album "was an experimental project with me scoring and doing other things I like: challenging myself with all the things that entered my mind from the Venus's Flytrap to Earth's creation to coming back as a flower."

That said, a return to pop styles would hurtle each of Wonder's four subsequent titles back to platinum status -- leaving 'Journey Through 'The Secret Life of Plants'' -- despite it having originally been subtitled 'Volume I-II' -- as more one-off than career redirection. There would be no 'Volume III.' Instead, 'Hotter Than July,' featuring the hit 'Master Blaster (Jammin'),' arrived less than a year later.