For the first 15 years that they were busy amassing one of the world’s most significant private collections of Dutch Golden Age art, Thomas S. Kaplan and his wife Daphne Recanati Kaplan kept a low profile, rarely identifying themselves as the owners of The Leiden Collection. But since they decided to go public in late 2016, Kaplan, an American investor, has been on a self-described “evangelical mission” to share Rembrandt with the world. English.