Les seuils empourprés (The Purple Souls) is the best-known of Lambert’s erotic work, building on the themes and techniques of his 1920 portfolio Dix sujets aimables dans le goût antique (Ten Lovely Subjects in an Antique Style). With the pseudonym Ansaad de Lytencia, which Lambert also used for a series of four prints entitled Caresses, the title page has the motto ‘Se trouve oû l'on peut, et se montre quand il le faut’ (You find it where you can, and it shows up when you need it). This must surely be as much part of Lambert’s personal journey as much as his artistic exploration. He also includes quotations by his favourite authors, Oscar Wilde and Baudelaire.
From ‘Initiation’ to ‘Finale’, the ten plates of Les seuils empourprés are among the most accomplished, both in composition and colouring, of all Lambert’s output. From an erotic viewpoint, they are also the most poignant and deeply-felt.
Les seuils empourprés was privately published in a limited numbered edition of 225 copies. In 1979 a high-quality limited and numbered reprint was produced by Media Productions in Brussels.