Men and women live in different worlds.
As part of my work with the Everyday Sexism Project, I've talked to children who are not yet sixteen but who understand a woman's place. They're used to being groped and grabbed on their daily commute in their school uniform. I've spoken to teenagers who all know a girl who has been raped, or assaulted, or had intimate photographs of herself circulated until she feels desperate and suicidal. I've listened to the women who have been assaulted and abused and then rejected by an asylum system that - irony of all ironies - refuses to believe their story because it is too awful to countenance. I've heard from elderly women who are grateful for the invisibility of age in a society that deems them worthless because at least it is better than their earlier life, full of harassment and assault.
The effect of living in a world where people of one sex are treated - in myriad tiny, indistinguishable, invisible ways - completely and utterly differently from people of another sex is enormous. You don't need to directly experience each individual component for this level of combined violence and oppression and prejudice to have a huge impact on you - on your life and your lifestyle, your ideas and ideals, and your fundamental perception of yourself and of the world around you.
"Male friends do not understand the problem and do not understand the way I hold keys in my hand as a weapon when walking alone just in case."
We think of men and women as living and working in the same world, and experiencing it similarly. But in many ways the manifestation of an identical event or activity by one might be entirely unrecognizable to the other.
"On nights out it has become the norm to have my arse grabbed, but the worst is when they grab for my crotch then disappear into the crowd so I don't even know who has done it (yes this has happened more than once and it hurts). I've also been threatened by men and pushed into walls for resisting or for standing up for friends they were trying to grope."
For most women, a night out means hassle and harassment, groping and unwanted advances, wolf-whistles and catcalls. Most men's experience of going to a club or bar, is manifestly different - though physically they are in the same space. This leads to a knock-on difference in our own behaviours. For many men, the countless routine steps women take to protect themselves - going out in groups and keeping tabs on one another, taking taxis to avoid badly lit routes, holding keys between their fingers, standing protectively together to avoid groping - are difficult to conceive of.
My experience of walking down the London street on which I live is completely different from my partner's, even though we live together, have similar schedules and both travel the route daily. He doesn't tense at the approach of a car in a distinctive shade of dark green, because it once slowed to a crawl while the driver told him, in chilling detail, how he'd noticed exactly which streets he regularly walked down and at what time. He doesn't cross the road to avoid the fishmonger's, where the men stand in the doorway making comments under their breath about his body as he walks past. He doesn't have to go to the coffee place that's a bit further away and without convenient WiFi because the waiters at the closer place harassed him and asked him for his number and made bets about who would get it the last time he went in. He doesn't duck into a shop doorway when he spots the man who once followed him off the bus and down the street. None of this crosses my partner's radar.
When he walks down the street he just walks down the street. But my experience of walking down the street is coloured by every one of these experiences and more, not just on the day they happen but every day after that.
All these differences in perception and behaviour also shape our more basic, foundational ideas of our own human rights and boundaries - our fear of assault, our assessment of our safety and our judgement of our own culpability.
"Until I heard you on Woman's Hour just now I thought it was all my fault. I have had experiences of sexual harassment all my life - the uncle who fondled my breasts as he comforted me when my father was dying in the next room; the supermarket manager who commented on my short skirt during my Saturday job and who said 'You shouldn't wear a short skirt if you don't want comments.' Then, as an 18-year-old civil servant, I was pushed against a wall and kissed and groped.
And all this time I thought it was my fault for sending out the wrong signals."
The world around us sends us messages about ourselves as women - about our guilt, and our difference, our accountability and our flaws. It gives us endless reminders of the vulnerability and victimization of women. It lets us know that it is normal and common for women to experience assault and harassment and rape. And it tells us that we deserve it. And all the while we are conditioned to be passive and pleasant, not to make a fuss - to be ladylike and compliant and socially acceptable. Before we ever experience violence we are conditioned to expect it - and to accept it.
"After a row with an ex-boyfriend about standing me up as he was still in the pub with his mates, he told me 'You should be thankful that I treat you the way I do. Loads of men are at home beating their partners.'"
"A co-worker who I considered a good friend at a new workplace came up behind me, wrapped his arms around my waist, and whispered in my ear 'Hey, mate, you know how I know we're having sex tonight? Because I'm stronger than you.' And fell over laughing because I instantly burst into tears."
Different worlds. It's what lets half the population laugh at something the other half lives in constant fear of.
Follow Laura Bates on Twitter: www.twitter.com/EverydaySexism