Whether you’re developing a building, planning transit, starting a company or just trying to do something different, there will always be haters. But pessimists don’t change the world—optimists do.

I came across a great post last night by venture capitalist Ben Horowitz. It’s called, “Can-Do vs. Can’t Do Culture." And I think you’d be well served to keep a copy of it on file and read it before every single meeting where you’ll be asked to provide input on something new.

He’s specifically talking about a growing and discouraging trend of naysaying in the tech community, but the lessons apply more broadly to innovation as a whole.

I love these lines:

"The trouble with innovation is that truly innovative ideas often look like bad ideas at the time. That’s why they are innovative — until now, nobody ever figured out that they were good ideas."

"From a psychological standpoint, in order to achieve a great breakthrough, you must be able to suspend disbelief indefinitely. The technology startup world is where brilliant people come to imagine the impossible."

But the best part of Horowitz’s post is an excerpt from an internal Western Union report (then the largest telegraph provider in the US) recommending that the company not purchase Alexander Graham Bell’s invention (the telephone) and patents for $100,000.

The Telephone purports to transmit the speaking voice over telegraph wires. We found that the voice is very weak and indistinct, and grows even weaker when long wires are used between the transmitter and receiver. Technically, we do not see that this device will be ever capable of sending recognizable speech over a distance of several miles.

Messer Hubbard and Bell want to install one of their “telephone devices” in every city. The idea is idiotic on the face of it. Furthermore, why would any person want to use this ungainly and impractical device when he can send a messenger to the telegraph office and have a clear written message sent to any large city in the United States?

The electricians of our company have developed all the significant improvements in the telegraph art to date, and we see no reason why a group of outsiders, with extravagant and impractical ideas, should be entertained, when they have not the slightest idea of the true problems involved. Mr. G.G. Hubbard’s fanciful predictions, while they sound rosy, are based on wild-eyed imagination and lack of understanding of the technical and economic facts of the situation, and a posture of ignoring the obvious limitations of his device, which is hardly more than a toy …

In view of these facts, we feel that Mr. G.G. Hubbard’s request for $100,000 of the sale of this patent is utterly unreasonable, since this device is inherently of no use to us. We do not recommend its purchase.

It’s a classic example of The Innovator’s Dilemma (a book written by management guru and HBS professor Clayton Christensen). Many firms see their businesses disrupted because they blindly stick to the innovation that made them successful in the first place—ignoring what’s coming up on the horizon.

In the case of Western Union, they could not imagine “telephone devices” in every city. The idea was pure lunacy to them. Of course to us today, they look like myopic fools. We now not only have telephone devices in every city, but a full fledged computer in every pocket. Imagine that.

Which is why I think it’s important to remember that the way to drive the world forward is—to use Horowitz’s terminology—through hope and curiosity. Suspend disbelief. Think big. Dare to be crazy. Because you’re only crazy until you’re proven to be a genius.