The brain is an incredibly important organ. You probably don't need reminding of this.
The brain has a similar consistency to soft tofu. It seems some of us might need reminding of this.
I say this because for all the sobering research and devastating first-hand accounts that have emerged in recent years about the dangers of concussion, it is apparent after the first part of the international rugby season that attitudes to head injuries are still infuriatingly lax.
Take some of the Twitter worship from well-known rugby stars when Wallabies loose forward George Smith returned to the field in the third test against the Lions just five minutes after leaving after a sickening head clash with Lions hooker Richard Hibbard. In his own words Smith "snake-danced off the field" after the collision, and in the eyes of many observers he was clearly concussed.
The decision to send Smith back on after the incident was foolhardy, yet on social media Smith was widely lauded as a hero for his "brave" return - not just from Wallabies fans, but some of world rugby's big names.
Ma'a Nonu reckoned Smith was "1 tough Mother", while Matt Giteau described him as "unbelievably tough" and former English international Will Carling has this to say: "George Smith back on! Fair play must have had some bloody strong smelling salts."
Fair play? No Will, bloody stupid play. Alarmingly, between the trio they have over 265,000 Twitter followers - Nonu's nonsense was retweeted 71 times.
There were similarly worrying attitudes coming from the All Black camp before their test series against France last month. Heading into the series, halfback Piri Weepu's role was in doubt after he was knocked out against the Highlanders in the final round before the Super rugby hiatus. He was stretchered off the field, but two days later a bubbly and bright Weepu was fronting media and reassuring everyone that he would be right to play in the opening test the coming weekend.
While All Black management and medical staff were saying all the right things about the need to take a conservative approach and manage Weepu's injury carefully, their messages were undone by the halfback's insistence that he was fine to play.
For all the work administrators are trying to do to educate the rugby community about the dangers of head injuries, it is clear a massive cultural shift is needed to tackle the issue and it is the game's stars who need to lead that charge. Rugby culture demands a tolerance to pain: getting up and playing on after taking a massive hit is seen as the mark of a courageous player.
When kids see their heroes playing on when they are obviously affected by a head knock, they think it is a heroic act; what they need to think is that they're being stupid. And that's only going to happen if stars like Nonu stop lauding head-injured players as being "1 tough Mother" and instead say "not cool, bro".