I was hasty yesterday morning, thinking of the Garden and sin and the balance between good and evil. And so, I listened to two audiobooks while at work, On Fairy-stories, and when I got home, I gently opened my 1971 paperback copy of The Tolkien Reader and began to read. Of course, I will have to reread it because it has been a while since I have, and I must admit, I could read it 100 times and still not comprehend it all. But I did find this in the Notes section B (page 32)
...
The least useful question, therefore, for literary critics at any rate, to ask or to answer about Iphigeneia daughter of Agamemnon, is: Does the legend of her sacrifice at Aulis come down from a time when human-sacrifice was commonly practiced?
Is the answer Iphigeneia, who like Éowyn would rather die heroically, winning renown, than be dragged to the alter/left behind?