That's easy! Rosy retrospection, positivity effect, there are a few biases going on here.

The "people of old" were just as intelligent as humans today, they just didn't have the same access to technology or stored knowledge (which is why Wikipedia is so revolutionary in some ways). If you look at the statuary from Classical times or the cathedrals of medieval Europe, you come to realize these people were just like us. Some went through life unthinking, others probably had unrealized gifts, and a few were able to show their talents. Also, I'm no anthropologist, but I believe modern humans have existed longer than wrting and the historical record, so I would conjecture that humans up to 10,000 years ago--perhaps all the way back to the Cro-Magnons of 40Kya--were just as intelligent as people today, just they didn't have the means to express it the way we do.

In some ways, the wasted educations and wasted talent of today is apalling. I was in the Sainte Chapelle in Paris recently and realized no one has created anything like it in 800 years.

I think it's a fantastic idea. The most difficult things for me to learn were always those which I don't know how to apply or those which I don't know where they came from. You can't reason over something that seems like magic.

For parallax you need to take two measurements at the same time. Given that the distance to the moon is about 384,400 km, a 1,000 km baseline gives an angle of 1/384 radians = 0.15 degree. This requires some a rather sophisticated methods, such as clocks with good precision and a telescope.

The method of Aristarchus is much more clever than that. At 1/2 moon, the earth/moon/sun forms a right angle. The angle moon/earth/sun could be measured as about 3 degrees - something that the ancient Greeks could measure. This gives a ratio of earth-moon/sun-moon distances between 18 and 20.

Then during a lunar eclipse, you can measure the width of the cone of the earth's shadow vs. the moon's width. During a solar eclipse you can see that the moon's angular width is about that of the sun. That information, plus the measured radius of the earth, and a bit of geometry, gives you an estimate of the size of the moon.

http://en.wikipedia.org/wiki/On_the_Sizes_and_Distances_%28A...

Michael S. Malone explores the "dark ages" idea in his new book "The Guardian of All Things:The Epic Story of Human Memory". His conclusion was that it was pretty dark for 5 or 6 centuries after Rome fell - then the "high Middle Ages" began and learning and writing and schools and scholarship were rampant all over Europe and the Middle East. Really opened my eyes on that period.

Islamic civilization took over from Roman civilization from about 632 AD in the Middle East, centered around North Africa, Iraq/Persia, and Turkey at various times over the next 1300 yrs.

Perhaps more important was the Sui/Tang dynasties in China around 600 AD kicking off over 1000 yrs of being the most developed place on Earth. They built the Grand Canal connecting the Yellow and Yangtse rivers, turning them into a single economy based on trading rice for coal.