in spades

Journal　２０１４年１月号のインタビュー記事、映画監督のOliver Stone氏のコメントから引用します。
He (J.F. Kennedy) said no, because he found his character. He looked into the abyss with Khrushchev, and he saw what the world was gonna come to. He saw hundreds of millions of dead, and he said no. And it took enormous courage, political courage, because he had, so many people were saying yes. He paid for the decision. He paid for that decision in spades.
私が覚えたいのは最後に出てきた "in spades" と言う表現です。English Journalの記事には注釈があり、 "in spades" は「確かに、はっきりと」となっているので、意味は直ぐに分かりますが、興味を覚えた単語に出会うと英英辞書を引く習慣になっているので、ここでも一応辞書を見ます。
・Cambridge English Dictionary: in large amounts or to a very great degree: My dog has personality in spades.
・McGraw-Hill Dictionary of American Idioms and Phrasal Verbs: in the best or most extreme way possible; extravagantly. He flunked the test in spades. He succeeded at life in spades - honors degree, great career, rich wife, lovely children, and early retirement.
上記辞書の説明はEnglish Journalの注釈と若干違う感じなので、更に他の辞書も見ます。
・Vocabulary.com: without question and beyond doubt: “she told him off in spades”
この説明なら確かに記事の注釈と同じですね。 "in spades" が何故この様な意味で使われる様になったのかは分かりませんでしたが、私の推測では慣用句の "call a spade a spade" と関係がありそうです。