Compare and contrast.
We teach that to our students to encourage critical thinking skills.
I had a lesson in it myself when I think of yesterday's experiences and today's.
Yesterday I spent the afternoon at Munich's Deutsches Museum of Science and Technology - the world's largest.
An amazing place - my favourite exhibitions were Physics, New Technology, and Tunnelling.
Yesterday was a glimpse of the beauty and power of human curiosity, human intellect, human collaboration.
Today I visited the concentration camp memorial at Dachau.
Today was an immersion into the dark side of humanity, it's ugliness, it's cruelty.
It was too much... one shouldn't visit a place like Dachau alone.
My head is bursting with thoughts and my emotions are reeling.
What one human can do to another human is inconceivable.