G. Stanley Hall, answered from the texts and cited to the page.
Adolescence is a second birth, and the most fateful passage of the whole life. In it the child dies and the man or woman is born; the old animal and savage nature, recapitulated in childhood, is overtaken by the distinctively human powers, which awaken all at once and unevenly — the sexual nature, the reason, the moral and religious idealism, the sense of the infinite.
Small wonder that the years are a time of storm and stress, of Sturm und Drang: of violent oscillation between exaltation and gloom, energy and lassitude, altruism and selfishness, faith and doubt; the time of conversion, of first love, of the highest creativity and the gravest peril of crime and breakdown. This turbulence is not disorder to be suppressed but the necessary ferment of a nature remaking itself on a grand scale, driven from within by the unfolding of inherited powers on their physiological schedule.
To understand the adolescent, and to educate and guard rather than thwart him, is the supreme task of a genetic psychology, for in these years the race renews itself and the individual reaches, or fails to reach, his full estate.123
Indeed, the chief fact of genetic psychology is conversion, a real and momentous change of unsurpassed scientific and practical importance and interest. It is one of the best criteria of the degree of culture of different ages, races, religions, and communities, how it is conceived, interpreted, formulated, and administered.Adolescence Vol 2, p. 358
Both modern science and genetic psychology supply new hints as to what is partly lost and partly might have been, or indeed may yet be when the scientific imagination supplements facts by heroic hypotheses, as Plato supplemented his positive teachings by the great myths which still so appeal to the heart and in later theological ages had more influence than even his doctrines.Adolescence Vol 2, pp. 190–191
At this age all may be said to be normally geniuses, some in slight and some in high degree, some for a flitting moment and some for life. Then at least the approximation to genius is closest, and those who blossom into full the efflorescence of creativeness do so by virtue of the energy that nature gives only then.Adolescence Vol 1, p. 321
Adolescence founded a scientific field and gave the modern world its enduring image of the turbulent teenager, and the "storm and stress" idea remains a live and partly confirmed hypothesis. The major challenge came from cultural anthropology: Margaret Mead's Coming of Age in Samoa (1928) argued that adolescent turmoil is not a biological universal but a product of particular cultures, and that a smoother passage is possible — a claim itself later contested. Modern developmental psychology finds a qualified middle: adolescent storm and stress is real (in conflict with parents, mood volatility, and risk behavior) but milder, more variable, and less universal than Hall's sweeping biological account held, and it interacts strongly with culture and context. The field is Hall's; the strong biological universalism is tempered.