All Quiet on the Western Front Identity Quotes

How we cite our quotes: Citations follow this format: (Chapter.Paragraph)

Quote #10

Perhaps it is our inner and most secret life that shivers and falls on guard. (4.21)

Even though Kat only supposes that there will soon be a bombardment, the soldiers are unnerved. What is this "inner and most secret life" to which Paul refers? Perhaps he is simply referring to the men's collected fears.