One incident of Bruno's childhood, which has been thought a promise of extraordinary powers, he himself relates in the _Sigillus Sigillorum_. Describing the different causes of "concentration,"[8] (_Contractio_), he instances fear among them:--"I myself, when still in swaddling clothes, was once left alone, and saw a great and aged serpent, which had come out of a hole in the wall of the house; I called my father, who was in the next room; he ran with others of the household, sought for a stick, growled at the presence of the serpent, uttering words of vehement anger, while the others expressed their fear for me,--and I understood their words no less clearly, I believe, than I should understand them now. After several years, waking up as if from a dream, I recalled all this to their memory, nothing being further from the minds of my parents; they were greatly astonished."[9] As well they might be! It is hardly right, however, to see in the story evidence of marvellous faculty showing itself in infancy, beyond that of an impressionable and tenacious mind. No doubt the drama had been repeated many times by the parents for behoof of visitors.[10] Superstitious beliefs abounded among Bruno's fellow-countrymen; many of them clung to him through life, were moulded by him into a place in his philosophy, and bore fruit in his later teaching and practice of natural magic. Thus we are told how the spirits of the earth and of the waters may at times, when the air is pure and calm, become visible to the eye. He himself had seen them on Beech Hill, and on Laurel Hill, and they frequently appeared to the inhabitants of these places, sometimes playing tricks upon them, stealing and hiding their cattle, but afterwards returning the property to their stalls. Other spirits were seen about Nola by the temple of Portus in a solitary place, and even under a certain rock at the roots of Mount Cicala, formerly a cemetery for the plague-stricken; he and many others had suffered the experience when passing at night of being struck with a multitude of stones, which rebounded from the head and other parts of the body with great force, in quick succession, but did no injury either to him or to any of the others.[11] It was at Nola that Bruno saw what seemed a ball or beam of fire, but was "really" one of the living beings that inhabit the ethereal space; "as it came moving swiftly in a straight line, it almost touched the roofs of the houses and would have struck the face of Mount Cicala, but it sprang up into the air and passed over."[12] To understand the mind of Bruno, it is necessary to remember the atmosphere of superstition in which he lived as a child. [Sidenote: Unity of Nature.]