Regarding Setanta's opinion on "left", the only thing that I got from his illustration is "left, in that context, is a combination of multiple meanings; it does not equal to the past participle of verb leave; so, it is abstract".
And then, ebBeth's interpretation helped me a bit, making my thinking clearer.
Still, I didn't get it very well.
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when men were left to ration stores, trusted with science expeditions, and left to enjoy their freedom.
(1) The first "left" is abstract, while the second is concrete -- the past tense of verb "leave"?
(2) mem were left alone, they just lived with their ration stores; in fact, they had to live with the boring stores. In this "chronic crisis", they met "science expedition", so they trusted with themselves to the expedition -- they thought the expedition was their savior. Thus, they got rid of their cumbersome situation - that is, they left their usual place, to enjoy their freedom.
(3) Or perhaps it means:
... for getting rid of the boring situation, they joined science expedition to enjoy their freedom.
Maybe "they joined science exjpedition" should be "they organized themselves as science expedition, and then to enjoy their freedom"?
Right?