Mydriasis eye, and also to reduce painful ciliary muscle spasm (see cycloplegia). One effect of administration of a mydriatic is intolerance to bright light (photophobia). Purposefully-induced mydriasis via mydriatics is also used as a diagnostic test for Horner's syndrome. Mydriasis can be induced via modulation of adrenergic or cholinergic signalling. Within the adrenergic system, norepinephrine is a hormone and neurotransmitter responsible for regulating physiological processes in the body, including the involuntary muscles of the autonomic nervous system (such as the dilation or constriction of the pupil aperture via the muscles of the iris). Modulation of norepinephrine signalling can induce mydriasis. For
What Is a Nation? and continues to be invoked. Political historian Karl Deutsch, in a quote sometimes mistakenly attributed to Renan, said that a nation is "a group of people united by a mistaken view about the past and a hatred of their neighbours". Benedict Anderson's 1983 work Imagined Communities, which states that a nation is an "imagined political community", argues that Renan contradicts himself when he says French people must have forgotten the St. Bartholomew's Day massacre, yet does not explain what it is. In other words, Renan assumes that all his readers will remember the very massacre he says they have forgotten.