There is nothing either good or bad but thinking makes it so.

As long as you are going to be thinking anyway, think big.

Whatever you think, that you will be. If you think yourselves weak, weak you will be; if you think yourselves strong, strong you will be.

I believe there exists, & I feel within me, an instinct for the truth, or knowledge or discovery, of something of the same nature as the instinct of virtue, & that our having such an instinct is reason enough for scientific researches without any practical results ever ensuing from them.

Even people who aren't geniuses can outthink the rest of mankind if they develop certain thinking habits.

That's been one of my mantras - focus and simplicity. Simple can be harder than complex: You have to work hard to get your thinking clean to make it simple. But it's worth it in the end because once you get there, you can move mountains.