Is it that the grand surroundings of the Royal Albert Hall deserve nothing but the very best performers?
Or is it that stunning music deserves surroundings as amazing as the Royal Albert Hall?
Whichever way round it is, everyone got the best last night when Broadway and West End superstar Idina Menzel brought her symphony concert to the historic London venue.
Menzel has been introduced to a new breed of fan with her appearances on Glee as Shelby - Rachel's biological mother and the former coach of rival glee club Vocal Adrenaline.
But while many more people may know her now, Glee is hardly the pinnacle of her career, which involves Tony nominations and wins, and the chance to originate one of the most famous roles in musical theatre - Elphaba the green witch in Wicked.
So, of course, Menzel sang numbers from the hit musical last night. Despite not being covered in green paint - she was wearing a stunning strapless off-white ballgown with a black ribbon belt and no shoes - her brilliant voice combined with her stage presence and acting chops made it seem as though you were watching Elphaba.
Menzel's ability to embody a character in a song was shown in a rendition of Love for Sale by Cole Porter.
The number was preceded by a story, as were most of the songs she performed last night.
Love for Sale's story had Menzel revealing she had a crush on a teacher at university, so when he told the class to pick any Cole Porter song, she thought she'd kill two birds with one song and use Love for Sale, complete with seductive looks and a costume consisting of lingerie-like items, and seduce said teacher and complete the assignment. Unfortunately for the young Menzel, she was stopped in her rendition and her teacher told her love for sale was not a seductive song, but a desperate one about a woman who is forced to turn to selling her body for money. Oops. And if that wasn't embarrassing enough, Menzel also discovered later in life that particular teacher was gay.
The humorous anecdote was a contrast to Menzel's performance of the song. She became the desperate woman for the few minutes she sang, uncertain, shy, facing up to her demons. And, in a brilliant arrangement, she also segued seamlessly into Roxanne by The Police midway through the tune before finishing Cole Porter's song.
For me, the highlight of the evening came near the end, with another song from Wicked. This time, though, Menzel simply played herself. Dedicating For Good to the crowd, Menzel shouted to the back of the hall that she would not be using her microphone, and to tell her if they couldn't hear her. They needn't have worried, her powerful vocals filled the hushed Royal Albert Hall, no technology needed. And it was one of the most emotional parts of the night, as Menzel sang straight to the fans who had been clapping and cheering all evening (guilty as charged).
Another spectacular moment also involved the audience, and was again an emotional, quiet performance. Menzel told of the death of the creator of RENT, who passed away on the day the cast had its dress rehearsal.
In tribute to the lessons she learnt from him and her time on the show, she sang No Day But Today, getting the crowd to sing the title line back to her towards the end, each time in hushed tones.
Sweet moments came when Menzel discussed her husband - Taye Diggs, who she met when she was in RENT - and their son Walker, followed by performances of silly songs the pair have made up for Walker ("my husband gets annoyed that my songs don't showcase his strong baritone, I get annoyed because his don't showcase my 13 octave range").
Funny moments came during a story about performing for Barbra Streisand (she ignored Menzel and Diggs as they sat at her dinner table, then asked if Menzel had sung for her as she'd forgotten her glasses, then abruptly left). And for the Glee fans Menzel poked fun at herself as she sang a stripped down version of Lady Gaga's Poker Face.
Menzel was accompanied throughout her show by the Royal Philharmonic Orchestra, masterfully conducted by legendary Broadway composer Marvin Hamlisch, one of just a handful of people to have won an Emmy, a Grammy, an Oscar and a Tony (an EGOT). He had a few funny stories of his own, during the very first short act which featured just him and the orchestra.
With a full orchestra behind her much of the night was loud, rousing and fun.
But it was the quiet, emotional, virtually solo numbers that truly showcased Menzel's talent, and which will stay with me for the longest.