There’s a famous exponential growth illustration that makes use of a chess board and grains of rice placed upon the board. Starting with a single grain, you double the quantity of rice on each subsequent square.
The punch line is that by the time you reach the 41st square, you’d need over a trillion grains of rice, and by the final, 64th square, there wouldn’t be enough grains of rice in the world to meet the square’s quota.
Exponential growth is a powerful thing. You start with a quantity (say, 4 billion people on the planet in 1975) and set a rate of increase (say, 1.9% per year), and then marvel over how quickly that number increases, if you give it a little time to percolate (6.43 billion people on the planet by the year 2000).
The power of exponential growth stems from all three variables. You’ve got a starting quantity, you’ve got a rate of increase, and you’ve got a duration over which you allow the growth to take place.
What’s great is that once you understand the concept, you can apply it to so many things. Monetarily, this kind of growth makes a strong argument for saving early and often (because the sooner you start saving, and the more you save, the more favorable the equation and eventual payday will be).
It’s also an excellent way to approach less-quantifiable sums, like experience and knowledge.
We may not have the math to describe such things in an absolute way, but the same general rules apply. The earlier you start learning and the more to which you’re exposed — the people, places, concepts, and everything else beyond the default environment you start with — the more personal growth you will experience over time (the rate of change in this example is your ability to take that knowledge and those experiences and expound upon them, making new discoveries, applying them to life, etc).
Even better, if you’re able to up your growth rate (by spending more time learning, exploring, trying and failing and sometimes succeeding, meeting new people, embracing self-improvement, and exposing yourself to new ideas), you can drastically increase your levels of personal growth (defined in this case by overall happiness and general wisdom) over time.
And finally, the earlier you get started, the longer your base knowledge, additional education, and experiences will have in which to evolve as you grow, allowing you to derive ever more from each adventure, each relationship, each job, each photograph, as time goes by.
The variables are different, years instead of chess board squares, wisdom instead of rice, but the math works out the same way. Invest as much as you can in living and experiencing and learning, as soon as you can, and the dividends you earn will be all the higher for it.
Update: April 12, 2017
The population of the world as of 2017 is estimated to be 7,515,284,153. The annual growth rate has dropped down to 1.11%.