Plz help Read this excerpt The First Men in the Moon.

For my own part a vivid dream has come to my help, and I see, almost as plainly as though I had seen it in actual fact, a blue-lit shadowy disheveled Cavor struggling in the grip of these insect Selenites, struggling ever more desperately and hopelessly as they press upon him, shouting, expostulating, perhaps even at last fighting, and being forced backwards step by step out of all speech or sign of his fellows, for evermore into the Unknown—into the dark, into that silence that has no end….
Which phrase in the passage above helps the reader infer the meaning of the bold word, expostulating?

shadowy discheveled Cavor
out of all speech or sign of his fellows
shouting...perhaps even at last fighting
dark . . . silence that has no end