In the year...say...1450, we knew - KNEW the world was flat. At one point in time scholars and church leadership argued (and took lives) over the idea of zero.  By argue I mean if you professed belief in the concept of zero or a vacuum, you were put to death. 

In 1895 men of science were sure that the atom was the smallest particle in the universe.  Human flight, space travel, flux capacitors all are ideas that at one point in time were simply unthinkable things that "could not be" realities. Ok, perhaps flux capacitors are still science fiction.

Many ideas still come to mind.  When my father played high school football in the 1950's it was believed lifting weights made you slow and inflexible.  The idea of staying focused on a vision in sports along with   the idea of preparing mentally through visualization would have been considered silliness.

Things change. Yesterday's certainty becomes folly tomorrow.

In his various seminars, Self Development Marketer extraordinairre Anthony Robbins discusses the idea of limiting versus empowering beliefs.  I am trying hard to remember where I first heard it expressed this way:  "There two kinds of people. There are those who think they can, and those who think they can't.  Both are [kinds] are right".

It is interesting to look at our ideas as a society through the lense of our beliefs as well. 

I wonder what ideas I have - and what ideas we have as a society -  right now, that will undergo seemingly radical, unthinkable changes in future.