I spend a lot of time working on ReTweets, mostly because I believe them to be one of the most important developments in modern communications, extending far beyond the Twittersphere.
“Ideas shape the course of history.”
-John Maynard Keynes
Ideas have been spreading from person to person for thousands of years; contagious ideas form the very foundation of human culture and history. Like “The Matrix” was composed of computer code, the real world is made of infectious information. Your chair, your desk, the computer you’re reading this on, the food you’ll eat today, the money you’ll earn; they all began as ideas jumping from person to person. None of it would exist if the concept wasn’t contagious.
For the last few millennia people have been telling each other about which god to believe in 
and which laundry detergent works best.
“There is one thing stronger than all the armies in the world, and that is an idea whose time has come.”
-Victor Hugo
Contagious ideas are the most powerful force in our world. Ideological epidemics have made and lost fortunes, they have saved countless lives and caused horrific wars, they have birthed and destroyed nations. Clearly the most powerful weapon known to man would be the ability to create powerful mental viruses at will. The very course of human history would be at your whim.
And remember, you don’t spread ideas just because they are “good;” you spread them because of some other trigger or set of triggers has been pulled in your brain. And that trigger fires the biggest gun ever seen.
Rudimentary attempts of this sort of engineering have been made to sometimes awe-inspiring ends; however, those successes have most often been based on luck and happenstance.
A reliable, repeatable method to craft a contagious idea has yet to emerge.
“If the Internet can be described as a giant human consciousness, then viral marketing is the illusion of free will.”
-George Pendle
The advent of the web changed how memes spread: it made them spread faster, it exposed them to 
more people, and it removed many of the constraints imposed by the limits of human memory. Obviously, post-web idea viruses are more contagious. But there is one change that dwarfs them all: observability.
Before we can purposely create a more contagious idea, we have to understand which elements make an idea contagious. The problem has been that for thousands of years there has been no way to observe memes in aggregate. Only anecdotal evidence could be analyzed, and, in areas like urban legends, rumors, and slang, these unreliable sources provided our only clues.
We can now compare millions of viral ideas to uncover the building blocks of contagiousness.
The structure of the web has made this sort of observability possible from a theoretical standpoint for over a decade. ISPs could have tracked email chain letters, or IMs from person-to-person, but technological and privacy issues prevented that.
ReTweets change all of this.
ReTweets may seem like a small idea, and they are. But that small idea is the first real window into how ideas spread from person to person. We can study the linguistic traits, the topical characteristics, the epidemiological dynamics, and the social network interactions that take place when a person spreads a meme.
Not only can this information help us create more contagious Tweets, but many of the lessons learned through ReTweets will be applicable to viral ideas in other mediums.
For the first time in human history we can begin to gaze into the inner workings of the contagious idea. That most powerful force can now be put under our microscope and probed for its secrets.
