Adherents of theosophist H.P. Blavatsky[12] have suggested that the third eye is in fact the partially dormant pineal gland, which resides between the two hemispheres of the brain. Reptiles and amphibians sense light via a third parietal eye—a structure associated with the pineal gland—which serves to regulate their circadian rhythms, and for navigation, as it can sense the polarization of light. C.W. Leadbeater claimed that by extending an "etheric tube" from the third eye, it is possible to develop microscopic and telescopic vision.[3] It has been asserted by Stephen Phillips that the third eye's microscopic vision is capable of observing objects as small as quarks.[13]