Sometimes, you need to be confronted with ugly reality in order to make you pause and think. This happened to me when I visited the Choeung Ek Genocidal Centre just outside Phnom Penh recently.
Also known as the Killing Fields, Choeung Ek was, before 1975, a 2ha orchard filled with longan trees and watermelons, although part of it was also a cemetery for the Chinese community nearby.
Between 1975 and 1978, however, this tiny plot of land became the execution ground for 20,000 Cambodians killed by the Khmer Rouge for no other reason than that they were educated city folk and not peasants.
It is a surreal experience visiting Choeung Ek.
For one thing, it is a silent place. In order to be respectful of the dead, visitors walk around with an audio guide and headphones that tell you the history of the place.
The guide even includes the voices of survivors.
It is hard to imagine the horror that took place in this quiet place but some of the exhibits bring the point home.
I remember seeing a piece of red rag, part of someone's clothing, on the ground and being caught between the urge to pick it up and the realisation that this was what some poor soul wore before he met his brutal end.
Or it may have been a child's shirt. One of the most unnerving sights at Choeung Ek was the "magic tree".
It is a tree on which hundreds of cloth wristbands are hung, in remembrance of the children and infants who died there.
They died in a way so cruel it brings shudders to the spine.
They were simply held by their legs and bashed against the tree until they died, often while their mothers were forced to watch.
Visiting Choeung Ek gives you pause to reflect on the nature of the human mind.
How was it that an otherwise gentle people could succumb to such collective madness that they were willing to kill so many of their friends, neighbours and even parents?
Three million people out of a population of only eight million died from starvation, torture or outright murder.
Anyone above 50 years old today would know someone who died in those hellish years.
Of course, this was not the only example of collective murderous brutality.
It has happened in Germany, Rwanda and Bosnia.
When you look at the types of torture and murder, including by beheading, practised by the Khmer Rouge, you can't help but think of the Islamic State today in Syria and elsewhere.
Human beings have a propensity to do this over and over again, it seems.
None of this happens overnight, although it can go from mild craziness to outright insanity in a very short while.
If you go to the exhibition on the site in Berlin of the former headquarters of the SS, the paramilitary organisation that was eventually found guilty of crimes against humanity for its role in the Holocaust, you will find some unnerving information.
They implemented Nazi policies, including the burning of books by authors labelled "un-German", marginalising those labelled political opponents or enemies of the state and using newspapers to spread Nazi propaganda.
"All men are not equal" was the slogan the Nazi leadership used to justify the exclusion and extermination of anyone who was not of Aryan stock, people they called sub-human.
Just as the Khmer Rouge defined anyone not a peasant as somehow a traitor to the "egalitarian" vision of society that they had.
As a society, we in Malaysia are not anywhere near these sorts of brutalities.
But it is easy to slip into a subtler version of the mindset without noticing.
Sometimes, the demonising of groups of people because they are different - due to nationality, religion, creed and class - trips off our tongues subconsciously. The use of the media to propagate discriminatory stories and untruths about people is becoming the norm.
The demand to prove our patriotism, loyalty and faithfulness or to be deemed traitors to nation and religion is a constant needling noise. The banning of anything that might make people think differently and question things is becoming a regular occurrence.
All these terrible events in history finally ended because there were people who retained their humanity and decided to risk their lives and do something about it.
In the end, it will always be the people who wake up from their stupor and take action who will save their country.
It is easy to either deny any such thing would ever happen to us, or to complain endlessly but ultimately do nothing.
Or worse, criticise those who are trying to do something at great risk to themselves.
Or is the Malaysian credo "As long as my nasi lemak is still there every day, I don't care what happens"?