One of the lessons of Katori Shinto Ryu practice is that just because something looks like it must be one thing, it's never safe to assume that it is. And this lesson seems to go on being taught and taught again, even after you first learn it.
Beginning students often lean back in postures such as ko-gasumi or te-ura-gasumi, since they believe they are blocking an incoming strike, and reasonably decide that the further away they are from that incoming blow, the safer they will be. Even after years of practice I find myself doing that without being aware of it. It's natural, to want to shy away from danger.
The problem of course is that ko-gasumi doesn't have to be a block at all. You learn after some practice that many of the maneuvers that appear to be blocks, and are practiced as blocks, are in fact attacks, carefully disguised to look like blocks. If I step backward, the incoming attack is blocked; but if I step forward, the attack is avoided and instead of blocking I find my sword striking down my enemy at the exact moment he sought to strike me.
If I do it right. And he doesn't see it coming. And a thousand other things that might go wrong don't.
But this is one reason why when we practice our stances, we work so hard to maintain a neutral if not a forward stance. We are never really retreating, and we must never forget to maintain a forward focus. To kill the enemy is the point of entering combat; many texts talk about the necessity to forget about self-preservation and think only of cutting down the enemy, whatever the cost to yourself. These are not empty exhortations, even in the safe sort of practice we engage in. It is something I should always be keeping in my mind. Whatever stance I take, whatever response the kata seems to be asking me to take, I need to constantly consider what is happening and how I can take the initiative, even when I seem to be blocking or retreating.
At the same time, I can't just move forward every chance I get. That's too simplistic for Katori. There are times when increasing the distance between your enemy and yourself is the right choice. I have to wait, pay attention, and learn to recognize when an opportunity presents itself.
The kata of Katori Shinto Ryu are not simple patterns to be memorized. They hold secrets and demonstrate options, many of which cannot be perceived by the casual student. It takes years of practice to uncover these truths, and this journey never truly ends. I am forever discovering assumptions in my practice that only now am I realizing are unfounded, and can be cut apart effortlessly by someone who has seen through them.
And leaning back doesn't help.