"In the books—the books that tramp has hidden—there are marvels, miracles!" (19.22)
Both Griffin and the narrator remark that Griffin's books contain wonders. That's pretty serious language that doesn't have a lot of ambiguity. It reminds us, too, how awe-inspiring science can be, both to scientists and non-scientists alike. We mean, come on, seedless grapes? Amazing!
"And you know the knavish system of the scientific world. I simply would not publish, and let him share my credit." (19.33)
This is another reminder that science is a community, with its own rules and traditions. These are some of the traditions that drive Griffin to do what he does (hide his research, test on himself, etc.). Turns out the Invisible Man is a bad member of both the scientific and the non-scientific communities. Looks like you're 0 for 2, Griff.
"And I beheld, unclouded by doubt, a magnificent vision of all that invisibility might mean to a man—the mystery, the power, the freedom. Drawbacks I saw none." (19.38)
Sometimes power is blinding. Period. Well, period plus one other thing. Notice the three benefits he mentions: "the mystery, the power, the freedom." Is he saying that power and freedom go together? What do you think?