“I was a failure as a boy and became a success as a man because I always was and always will be Archibald Alexander Leach, only I became better at hiding it than he ever could.”
Fragments of this sentiment do appear in Grant's 1963 autobiographical series, but the sentence as quoted cannot be found in that text or in any other primary source. It reads as a later paraphrase hardened into a quotation.
On the same subject.
“Well, on the contrary, the process of turning a man into a woman is enormously complicated, but I’ll do my best.”
Cary Grant as Capt. Henri Rochard · 1949
“I learned that you appreciate work most while you’re at leisure, and leisure while you’re at work. It’s like being married or single. You can’t be both at the same time.”
Cary Grant · 1961
“Ah, Maggie, in the world of advertising, there’s no such thing as a lie. There’s only the expedient exaggeration.”
Cary Grant as Roger Thornhill · 1959
“My name is Rochard. You’ll think I’m a bride but actually I’m a husband. There’ll be a moment or two of confusion but, if we all keep our heads, everything will be fine.”
Cary Grant as Capt. Henri Rochard · 1949