Linguistic sounds, considered as external, physical phenomena have two aspects, the motor and the acoustic.
Roman JakobsonEvery linguistic sign is located on two axes: the axis of simultaneity and that of succession.
Roman JakobsonLanguages differ essentially in what they must convey and not in what they may convey.
Roman JakobsonSemantics, or the study of meaning, remained undeveloped, while phonetics made rapid progress and even came to occupy the central place in the scientific study of language.
Roman Jakobson