I'd recommend it strongly. I really like some things about it - first, it divides horses into 16, not just a few, personality types, based on pairings of dominant/submissive, energetic/lazy, curious/afraid, and friendly/aloof. It also recognizes that, even within these personality categories, each horse is an individual who may lie far to one end of a character pair, somewhere in the middle or can even switch between - our Dawn, for example is both very strongly curious and very strongly afraid, which makes for some interesting challenges. There is a chapter on each horse type with excellent descriptions and also some very good detailed training suggestions. There is no one-size-fits-all training method - I've believed this for years, which is one reason I don't believe "training systems" suit the best interests of horses - they suit the best interests of trainers who sell the system and owners who want a program to follow (which, to be fair, inexperienced horse people may really need to get started). Horses, and people, are much more complex that this. I think it's important to have a kit of training tools (by which I don't mean gadgets or tack or equipment; I mean a variety of ways of thinking about and approaching a training task with a horse which depends on the specific horse and the specific circumstances), but to always be flexible and willing to rethink and adapt.
Another thing I really like about this book is that it makes the important point that our own personalities enter into the picture too when we're working with horses, and that in some cases we may have to modulate how we would normally act when dealing with a particular horse - for example, if we're very dominant and our horse is also very dominant, we will have to avoid getting in fights with our horse, which will be our natural tendency. We have to be aware of our own strengths and weaknesses, and may sometimes have to grow and change, to work effectively with horses. I've certainly found this to be true for myself.
There is also a very good section on the use of the round pen, and how it can be misused or properly used in a training program, once again depending on the specific personality traits of each horse. Very good stuff. I don't agree with every last detail in this book, but it's very useful and I would recommend it.
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Maisie seems pretty happy to be back at our barn - except when she' stuck in her stall when the other horses are out - then she whinnies and body-slams. She hasn't had any grass in almost two months, so we're reintroducing her slowly - she was pretty excited when she got to graze for 15 minutes yesterday. She got to go out with the mares briefly - she hasn't been out with another horse in two months either. All of the mares already know her but there was much posturing by Dawn and some running around. This morning for a few hours she's in a smaller dry lot with Dawn and two piles of hay. Dawn's strutting around the paddock, going "SQUEEEEE" and doing her "Spanish-walk" strike out with one or both front feet. Occasionally she'll go up to Maisie and sniff her legs and belly - Maisie stands very still and keeps an ear and eye on Dawn, so when Dawn reverts to her posturing Maisie can quickly move away. So far Dawn shows no inclination to chase her or attack her, and Maisie's pretty good at reading the signals and is also very submissive.
Before her turnout yesterday, Maisie and I went on a brief trail ride. She was pretty excited but listened well - even when the mares in turnout spotted her and came running up to the fence. If we don't get rain I hope to do the same today before she gets her brief (30 minutes) turnout with the mares this afternoon. It's great to have a happy horse again!