Plain and simple: Perfect is a myth because one man's trash is another man's treasure. In theory, the perfect book would be beloved by everyone. Is there such a thing? I've heard of popular books, but not perfect ones. There's always someone out there who doesn't like a book for some reason or another.
There's no such thing as perfect. There's only perfect to us. And even then as we change, our perception of perfect changes too. Things we loved a long time ago, don't have the same meaning or are skewed through nostalgia.
It's like how a song can take you back to a time, place, and feeling, but can never fully recapture the moment. An echo, however powerful, isn't the same as the direct source.
It's the same concept with writing. What seems perfect one moment will ultimately change under the scrutiny of time and distance. Thus, perfect becomes imperfect. And the view that we had of our mind baby crumbles to dust and leaves us feeling insecure about our abilities. After all, if we were that bad but thought that we were good, how bad are we now? What if we're never good enough?
That insecurity either shuts us down or drives us to chase the vision of perfect, and the loop begins again. Discouragement's powerful grip takes over; Disgruntled and distraught, we give up altogether. Or we keep plugging along and comparing our imperfections to those pieces we deem perfect.
A lot of writers are perfectionists which hinders their natural abilities. Even beginning is a hassle when you say, "I'm not going to begin until perfection flows out of me." Perfection isn't achievable as is. If you wait until it flows out of you, you'll be waiting forever.
Step out of the realm of believers in "perfection." What you'll find there are haggard souls just hoping that one day perfection will settle on them like a gift from the Gods. It never comes.
As Steven Pressfield intimated, The muse doesn't wait for perfection. She doesn't expect you to be a perfect writer before she imbues her ideas into you. She waits for dedication, for the will to try, for the will to fail and most of all for the will to succeed. (I'm just paraphrasing here.)
The muse waits for a steely-eyed (if somewhat moon-eyed as well) participant with which to bestow her gifts.
Don't get caught up chasing perfection. Nothing can ever be perfect because perfect is a moving target. But what if we aim at a different target? What if we aim for Excellence?
How about just saying to ourselves, "I'll just write. And then I'll make it better."
"Good enough" is good enough to get started. Even just a mad dash at the keyboard or paper to get all the ideas down is perfectly sound writing practice. Editing comes later, and it must come later. But for now, put your hands on the keys or the pen to paper and just write.
Forget so-called 'Perfection.' Just aim for your best.