The early stages of Keith Urban's relationship with future wife Nicole Kidman could well be summed up in two simple words which the Oscar-winning beauty softly uttered to him when they first began dating. The words would also inspire Keith to write a song called 'My Heart Is Open,' which can be found on the country superstar's current album, 'Defying Gravity.'

"That song came from a conversation I had with my wife ... when we had just started dating," Keith tells Tacoma, Washington's News Tribune. "I asked her how her heart was, which is a really strange [question]. I don't know why I asked that question the way I did, but I guess it was just a way of finding out -- where are you at? I don't know... is there a chance for us to go forward?"

Nicole's simple and poignant response? "It's open."

"I was really taken aback by that answer on so many levels," Keith reflects. "I thought it was an amazing thing to say, a really brave thing to say, to admit that to me. And I guess it made me ask myself, too ... is my heart really open? I mean, I think it is, but maybe it isn't. Maybe I've got it a little bit closed, because it's terrifying to let somebody in."

Keith adds that Nicole's influence on 'Defying Gravity' can't be understated, saying, "The love of my wife can be felt throughout the record because it was a huge part of my journey throughout those two previous years of 'Love, Pain and the whole crazy thing,' through making this album."

Keith says the album ultimately wasn't just about finding love, but about asking himself if he had the courage to love. And now that he seems to have answered that question, he's giving fans on the Escape Together World Tour the chance to hear songs from that romance-inspired album and others throughout his career.