The second postulate is stated as: Light is always propagated in empty space with a definite velocity c that is independent of the state of motion of the emitting body. It could be rephrased as: Light is always propagated in empty space with a definite velocity c independent of the fact that the source is in a state of rest or in a state of motion relative to the observer who measures its speed. 1. Is "the source is in a state of motion" a direct consequence of the first postulate? 2. If so, then a result obtained from a scenario in which the observers are not obliged to measure the speed of light emitted by a moving source could be considered as a conseuence of the first postulate? Thanks for your answer.