On Writing What You Know, or Not

One of those powerful dicta that newbie writers receive many times is, "Write what you know."  It certainly worked for Flannery O'Connor and Thomas Hardy to sink body and soul into the places that ran in their bone marrow, to use the accents and verbiage of their homebodies, to ignore the rest of the universe.  Each of them sought the commonality of humanity in the specifics of their own villages and towns, farms and roads, libraries, ramshackle cars or carriages, and tired feet.  But is that the only way you can write anything worthwhile?  What about Blind?  Who has experienced what it would be like for everyone to become blind at a stroke?  Yet it's a profound novel, well worth reading, with great insights into human behavior and emotions.  I've thought a lot about this advice, and I think it can inhibit creativity. Its virtue is that you are likely to know the important details of places you've lived and loved.  But it can prevent you from applying those details to new places and ideas.  And here's the real rub.  You can tell yourself you know a place and its people, but the insides of their heads could be much different than you imagine.  So unless you talk about the world according to your own thoughts, there is no real way to write only what you know.  And if you talk with any philosophers, even your own thoughts will have fading reality.  So, I'd say this.  Keep in mind rooting what you write in the physicality of the universe you're describing.  But let your imagination go free in placing your writing in Stonehenge, on Mars, or in a time and place of your richest desires.  And enjoy yourself in that world.