…persistently when they were in his work-room, putting arguments for and against the probability of certain biological views; but he had none of those definite things to say or to show which give the waymarks of a patient uninterrupted pursuit, such as he used himself to insist on, saying that "there must be a systole and diastole in all inquiry," and that "a man’s mind must be continually expanding and shrinking between the whole human horizon and the horizon of an object-glass."
There are no more uses of "systole" in the book.
Show samples from other sources
For everywhere she looked, everywhere she turned, was the rhythm, and as it continued to control the systole and diastole of her heart, the intake and outlet of her breath, the red miasma began to creep before her eyes again, and she was afraid that she was going to lose consciousness, and if she did that she would he completely in the power of IT.
Madeleine L’Engle -- A Wrinkle in Time
Cotton was the heartbeat of the section, the planting and the picking were the diastole and systole of the red earth.