For years shrinks have been telling us that we must know ourselves before we can begin to understand others.

Since few of us ever fully understand ourselves, how are we expected to truly know our friends, neighbors, acquaintances or even our closest family members, or what motivates them to do anything.

With that in mind, how can we analyze the motives behind Bruce Jeffrey Pardo, who masterminded the massacre of eight people at a Christmas Eve party.

In a scene more reminiscent of the most gruesome horror movie than the season of peace on Earth, goodwill toward men, Pardo, dressed as a gift-bearing Santa, entered his ex-in-laws home in a quite Covina neighborhood and began killing.

Described variously as “quiet, unassuming, nicest guy, always a pleasure to talk to, and always a big smile,” by those who were acquainted with him, immediately began trying to figure out what made him commit such an unthinkable crime.

Speculation isn’t limited to those who knew Pardo, but include, police, media commentators and everyone who heard the story.

Those all too familiar words in describing a rampage killer as “quiet, unassuming, nice, kept to himself” were echoed here, too. We hear them after every killing by someone who is assumed to have acted out-of-character.

It doesn’t matter that Pardo served as an usher at Christmas Eve services at his church for the last eight years, was kind to animals or any other good thing one could say about him.

Proof of that is the pedophile scandal that rocked the Catholic church where supposed men of God and church sexually abused children for years and the church covered up their crimes.

How many of us really know our neighbors? I’ve know some of mine for years, but I don’t live in their houses any more than I live in their minds.

I always assume that all of us are capable of doing anything at any time depending on hard we’re pushed.

I have one neighbor kills everything that flies, walks or wiggles its way into his yard. Another used to have such severe fights with his wife that he could be heard down the street. One fight was so raucous paramedics had to be called because he suffered some kind of attack. The worst for nosy neighbors was that they fought in a foreign language and we didn’t even know what the argument was about.

Another neighbor always looks like he’s angry until you talk with him and you discover he just looks like that. One woman is a moody witch and you never know how she’ll snipe at you. Another always talked to her kids in the most derisive way when they were young.

None of the above means that any of them will go off half-cocked and “off” their entire family.

The closest example we have of not knowing why people do what they do is our own impulse buying, but that doesn’t have devastating results.

Even if you know someone is the “weirdest” person alive, does the strangest things, and you’re sure he’s capable of a Charles Manson- or Night Stalker-type crime there’s not a damn thing you can do about it. We can’t lock people up before they commit a crime.

How often have we heard of people who killed family members, then turned the gun on themselves? With that, we’ve wondered why they didn’t just kill themselves first?

Pardo’s killing of eight people wasn’t a spur of the moment, lose control thing. It was carefully planned.

Police investigators said Prado, brought a sophisticated fuel spraying device with him to burn down the Covina house after his murder spree, left an incendiary device in a car, another car without any device, weapons, ammunition, $17,000 in cash and an airline ticket to a foreign country with him.

That indicated he was planning to escape the country after his murder spree and not bent on committing suicide, which he ultimately did.

His body was found to have been severely burned, leading to speculation that his injuries were suffered while torching the murder scene house causing him to flee to his brother’s home in Sylmar where he killed himself.

He could have had a severe case of killer’s remorse. We’ll never know any more than we’ll know what motivates any person to commit such a heinous crime. They probably don’t know themselves.

The bottom line is to never try to figure why people do what they do. Even the most seemingly altruistic act can have ulterior motives.

There are two lessons to be learned here:

One, is never allow children to open the front door.

Two, if someone is at the door who’s been giving the family trouble -- whether it be a family member, former family member or friend -- don’t let him in, and if he won’t go away…call the police.

You never know what someone is capable of doing.