Masterful singing. A seamless blending of the registers, very supported, full, and deep breathing, angelic pianissimos, gorgeous phrasing, not to mention a plain old gorgeous voice. Later in the opera, which calls for some big, loud high notes -- Legay doesn't shine. It's these leggiero singers with smaller voices like Legay, Sousay, Vanzo, or even Wunderlich, that are each more precious than 10 spintos. Anyone can blast Cavaradossi. Only a few singers can do justice to En fermant les yeux.
This is from Act 2 of Manon, by Jules Massenet. The naive Des Grieux feels Manon's 16 year old attention fading, so he tries to coerce her into living out his dream with him.