One of the rejections I got (the agent sent me all of them...man, was that depressing!) stated that they were publishing a similiar book this fall. Most of them wrote they didn't think there was a market for it.
These comments on rejection slips seem to indicate the problem is not professional presentation of the ms...

I'm wondering if you really have your market clearly defined. Who wants/needs this book? How many of them are there in North America? What other similar books are there on the market? (If the answer is none, you may actually have problems...) If the answer is more than none, how is your book unique?

I'm not certain publishers really want to know how valuable your book is to humanity. What they want to know is who's going to buy it. Does your query answer that question?

That being said, I think our black swan friend has some important points, too. I'm just assuming that you've taken care of them already...

And I like Frank's advice about cruising bookstores for possible agents/publishers. I do it myself in the fiction arena.