out on a limb

Shirley MackaineのOUT ON A LIMBを読んでいます。
タイトルとなった "out on a limb" がやっとでてきました。不倫相手の英国の政治家Gerryとの密会での別れ際の場面です。
As he retrieved his glasses from me he said, "When is your birthday?"
"April twenty-fourth," I said.
He nodded as if to say it was another date in the future he could look forward to. Then he said, "What do you think we have together?"
I sighed and ran my fingers over the hair in his eyes.
"I know," he said, "to get to the fruit on a tree, you have to go out on a limb".
He looked into my eyes and walked away.
霊媒(trance channeling)に興味を持つようになったShirley Mackaineは霊媒師のKevinに会いますが、霊媒師も "out on a limb" と言う表現を口にします。。
"Because it is considered to be a ludicrous waste of time. Superstition and the like. Serious people who admit to such investigations are sometimes made to feel ridiculous. But as a friend of yours said recently, "To get to the fruit on the tree one must go out on a limb." I was silent--floored. He had used the same analogy as Gerry. I had been most careful never to even mention Gerry to anyone, much less what he said.