I've only been able to sing by ear, singing out of my ears or eyes always gave me a headache, & made me look as if I were crying. Up until the past couple years like others here I only sang solo. Then I started teaming up with a few others, two sing it alls, they talked a different language, but it was amazing to see the above Jerry pull harmonies off a page where no harmonies were written & the not here Neil see & hear where Jerry was leading to, in his head & try to tell me where to go before one bar had even been sung. All the while I'm going through my trial & error routine, it worked but it was then I realized that having both capabilities & not just one can make a world of difference. Reading the music plus knowing the theory so that the two work for you hand & hand removes limitations that only enhances the enjoyment of singing with others. Good night. Barry