Two periods can be distinguished in the past history of our subject. The first period, which begun about 100 years ago, was dominated by intensive studies of novae and U Gem type stars at their outbursts and led to a fairly detailed, photometric and — particularly — spectroscopic description of these phenomena. The faintness of all these objects at minimum was a seriously hampering circumstance for observing them spectroscopically outside of their outbursts and it was only about 30 years ago that two pioneering surveys — of novae by HUMASON (1938) and of U Gem type stars by ELVEY and BABCOCK (1943) — begun to unravel their true nature.