The phenomenon has been discussed by thinkers as far back as Aristotle, who felt that perhaps the heat of the sun on the nose elicited the response. However, closing or shading the eyes seems to prevent the reflex, indicating that Aristotle was not quite on track scientifically with this theory. If the heat is still there but the sneeze can be prevented that must not be the cause.
Others have argued that bright light causes the eyes to water and the moisture irritates the nasal passages. Francis Bacon was an early author of this theory. But modern science now shows that the sneeze effect takes place too quickly to be the result of a chain of physiological events.