After the success of Barbarella, Forest could do anything he wanted and what he wanted to do was adapt Jules Verne's The Mysterious Island in comic form for children! After the first two segments appeared in the French children's magazine Pif Gadget in 1970, it was deemed "not for children" and the rest of the adaptation didn't see publication until it was released as an album--for adults.

From the publisher:

Discover the magical and incomparable universe of Jean-Claude Forest. Mystérieuse, matin, midi et soir is a very personal interpretation of The Mysterious Island by Jules Verne. This masterpiece, produced in 1970-71, is the first reissue of Forest at L'Association. Here in a previously unpublished black and white version. To be placed urgently in any self-respecting comic book library.

Résumé

Mystérieuse, matin, midi et soir est le livre idéal pour découvrir l'univers magique et incomparable de Forest. Interprétation toute personnelle de L'Île mystérieuse de Jules Verne, le chef-d'œuvre de Forest, réalisé en 1970-71, est la première réédition de Forest à L'Association, dans une version inédite en noir et blanc. À placer d'urgence dans toute bibliothèque de bande dessinée qui se respecte.