I have been re-reading Malcolm Gladwell's great book The Tipping Point. Great read.

This book explores how ideas spread, how movements start. It should be interesting to anyone who cares about the spread of ideas. He has a great Illustration of the power of doubling. I used this story for years and had forgotten about it.

Consider, for example, the following puzzle. I give you a large piece of paper, and I ask you to fold it over once, and then take that folded paper and fold it over again, and then again, and again, until you have refolded the original paper 50 times. How tall do you think the final stack is going to be?

In answer to that question, most people will fold the sheet in their mind’s eye, and guess that the pile would be as thick as a phone book or, if they’re really courageous, they’ll say that it would be as tall as a refrigerator.

But the real answer is that the height of the stack would approximate the distance to the sun. And if you folded it over one more time, the stack would be as high as the distance to the sun and back. This is an example of what in mathematics is called a geometric progression. Epidemics are another example of geometric progression: when a virus spreads through a population, it doubles and doubles again, until it has (figuratively) grown from a single sheet of paper all the way to the sun in fifty steps.

A group of ten that doubles every 18 months can reach 1000 people for God in 10 years. It is an indisputable fact of mathematics. Think it can't happen in the real world? Think it can't happen in church world? Think it can't happen with groups? I'd like to recommend two more books:

• Exponential by Dave Ferguson. It is the story of how Community Christian Church grew from a handful of college buddies to a thriving multi-site movement of churches. It is all based on doubling groups. They started a small group, then they divided and each led a small group. Now they are doubling churches on the same principles they used to double small groups.

• Viral Churches by Ed Stetzer and Warren Bird. It is the story of a dozen movements like Community Christian. 

Doubling groups can happen and doubling groups are amazing. I just can't quit thinking about it.