As a solo artist, Morrison, a rock troubadour if there ever was one, is a mesmerizing performer. He commits to his music to such a profound degree you cannot help but be swept away by it. I love two comments over at youtube about him: "Van could sing 'take me out to the ballgame' and bring me to tears," was one; the other, "It's more like a soul with a voice than a voice with soul."
Of all the songs on his 1971 recording Tupelo Honey, You're My Woman is the pinnacle. Rolling Stone called it "one of the genuine masterpieces of Van's recording career." At 6:40, the song builds and builds to such emotional intensity that I sometimes can't stand it but never want it to end. It is a love song of monumental proportions, one of the best I've ever heard.
The accompanying horn, piano and rhythm section arrangements on this are also exquisite. This song isn't anywhere to be seen on youtube, but if you want to witness the Irish dynamo in his element, check out this gem as a substitute. Something else to look for: Martin Scorcese's series on the blues, specifically the Red, White & Blues episode that Mike Figgis directed. Here you'll see an astonishing session with Van, Tom Jones and Lulu, accompanied by Jeff Beck. For anyone who loves the blues, I can't overstate what a treasure it is.