Around our house in Eclépens, Switzerland, in summer there are the hot air balloons. Colourful balloons often appear, floating peacefully in the sky from behind the hill in front of our house. Gaia, my daughter, never misses one, "Daddy, a hot air balloon!" For her, they are magical objects, and for us, they also have their charm—part ancient and part playful with their vibrant colours. Then, when they leave, they disappear behind the horizon of the hill. In that moment, Gaia wants to know where they go and what they do; and so, the stories of the hot air balloons were born, told before bedtime every other night.