Mathematics is of two kinds, Rigorous and Physical. The former is Narrow: the latter Bold and Broad. To have to stop to formulate rigorous demonstrations would put a stop to most physico-mathematical inquiries. Am I to refuse to eat because I do not fully understand the mechanism of digestion?
"Oliver Heaviside (1850-1927) — Physical Mathematician" by D.A. Edge. Teaching mathematics and its applications: An International Journal of the IMA, Volume 2, Issue 2, pp. 55-61, 1983.
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