The most famous of the pieces, Sommarsång (Summer Song) recalls the warm, calm, harmonious and bright pre-summer evenings where the sun in the north almost never goes down; they were the great breakthrough for Wilhelm.

Sommarsång is still known to most Swedes, even to people generally uninterested in music: the majority of young piano students in the Nordic countries have been taught this piece.

Domedagsprofeterna is the antithesis of Arnljot – a light festive musical comedy set in 17th century Uppsala, while the saga Adils och Elisiv where Swedish ‘talsång’ (speechsong) attained its purest expression is a work extolling Peterson-Berger's belief in humanism and the goodness of man.

[4] One acquaintance later recalled his surprise when, on a journey by train from Stockholm to Östersund and Frösön, the big man and notorious critic suddenly burst into tears and felt soft like a child as the bucolic landscape of his beloved Jämtland began to unfold outside the window.

The downstairs music hall has his grand piano (he was a competent pianist), a work room (with a ‘picture window’ looking out over Storsjön) and library (with his collection of books and scores), while upstairs the bedrooms may be viewed.