by jove, i think he's got it

Etymology:

• The origin of the phrase is often attributed to the character Henry Higgins in George Bernard Shaw's play "Pygmalion," which was first performed in 1913. However, the exact origins of the phrase may be difficult to pinpoint, as it has likely evolved over time through common usage and cultural references. In 1958 the Broadway musical adaptation was called "My Fair Lady" and the phrase was "By George, I think she's got it." The term "By Jove," short for Jupiter, the Greek God of the sky, is an old English euphemism for "By G**" that people use when they don't want to take the Lord's name in. Over time the phrase morphed into "By George" as well