In the fireflies books he used a technique sharply contrasted with that on Bruin the Bear. The insects are drawn with thin lines, and he creates a world of tiny creatures dressed in period clothes, their behavior in keeping with these. By tiny touches, such as the angle at which he sets the eyes, antennae and wings, he indicated the dream world, the world of insects.

The full-page illustrations are in bright coloured paint thinly applied. Trnka used a kind of spiral composition, building up his ideas from the top downwards. By linking certain shades of colour, and by the used of thin lines, he managed to convey the idea of weightlessness and irreality. The dream became real, and reality turned back into a dream.
This variety of techniques led only gradually to a unified style. Trnka was feeling his way towards it, and it took him some time to find it. But the basic concept never changed. Trnka did not illustrate scenes or situations. He mirrored the atmosphere, the dramatic or poetic meaning of the story.
The first book in which his individual approach as an illustrator took definite shape was Susan Discovers the World, by H. Chovokova. It was, in face, a little book written by his wife about their daughter Susan's first steps into the bigger world, and it was a powerful source of inspiration to Trnka. It had double-page illustrations in which he developed his notion of reality combined with dream in a way which was to become typical of all his work, not only as an illustrator. For the first time, he used a number of separate events to compose on illustration, placing them side by side for the sake of their association, at times superimposing or overlapping them, or linking them by an inner poetry, stressed outwardly through colour.
By painting the dreamlike aspects of reality Trnka was doing the same as the surrealists, but his illustrations have none of the cruelty or artistic ruthlessness of surrealism. His roaming brush reflected a child's roaming mind, with is inability to concentrate, its tendency to fantasy. He created a world where a lion leaps out of the sea on to the shore; where bears on ice floes admire floating roses; where the body of a drowned man sinks to the bottom through the seaweed; where a princess lights a stove, and a rider calms his prancing horse. The events seem unconnected, but everything is really subtly inter-related and full of magic, like and enchanting fairy-tale vision. Trnka had the first of endowing animals and things with mysterious and splendid inner life. His baby elephant suggest a toy for a small child; his water-lily a cradle. He draws a fish telling a fairy tale. His squirrel, hare and fawn are companions. Remote objects seem close, intimate, utter gentle.
Even where he did not use puppets as models, his figures were reminiscent of them. He never attempted to conceal that he was at heart a puppeteer. He drew attention to the relationship between his two medium of expression in his first exhibition.
This was held at the Arts and Crafts Museum in Prague, between November 29th and January 5th, 1941, under the title ‘The Children's Painter'. Trnka laid his complete work before the public, putting his puppets side by side with his illustrations. He showed no only the puppets from the Wooden Theatre, but also those private puppets which he had continued to make over the years, for no special purpose: the old decorative puppets of characters from Shakespeare, or inspired by the words of Maeterlink, Zeyer, or Mozart. And by their side were new ones, made in his spare time, as a realization from the tension of the work on book illustrations. Like the toys his mother had made, they were sometimes of rag. Trnka had an understanding of the quality of material, and he could use fabric to express character. He made rag figures of Indians, foresters, chimneysweeps, old men, musicians. They were all charming, in spite of their clumsiness. They were intended as children's toys, and were sewn by Trnka himself, though he had designed them with an eye to mass production. He had dreams of replacing the ordinary mass-produced dolls, which he though inartistic and unsuited to children's psychological needs. He put his rag dolls on exhibition to attract the attention of the public and also the toy makers.
‘The Children's Painter' exhibition was the event of the season. Its great attraction was the diorama The Insect Wedding, which excited the small visitors, and even won praise from the art critics, who were generally niggardly, since they did not take puppets and children's book illustration seriously. The response from the public and critics established Trnka in his position in the forefront as an illustrator.
One thing disappointed him, however. They toy-makers did not show the interest he had anticipated. There were some voices raised in the Press, drawing their attention to Trnka's dolls, but nothing came of it.
Trnka's second more carefully planned attempt to bring his puppets to life had failed.