英文についての質問です。
This argument, so often cited as a premier example of reason at its most perfectly and preciously ridiculous, was most seriously and comprehensively set forth by the British naturalist Philip Henry Gosse in 1857. Gosse paid proper homage to historical context in choosing a title for his volume. He named it Omphalos (Greek for navel), in Adam's honor, and added as a subtitle: An Attempt to Untie the Geological Knot.
Since Omphalos is such spectacular nonsense, readers may rightly ask why I choose to discuss it at all. I do so, first of all, because its author was such a serious and fascinating man, not a hopeless crank or malcontent. Any honest passion merits our attention, if only for the oldest of stated reasons--Terence's celebrated Homo sum; humani nihil a me alienum puto ( I am human, and am therefore indifferent to nothing done by humans.)
(Adam's navel by Stephen Jay Gould)
1） 出だしのThis argumentというのは、前回質問させていただいた（https://okwave.jp/qa/q9315469.html）中にあるmany earnest people of faith had wondered whether Adam had a navel.の個所を主に指していると思うのですが、
（もう少し議論の内容を述べると、以下のような感じだと思います）
★He was, after all, not born of a woman and required no remnant of his nonexistent umbilical cord. Yet, in creating a prototype, would not God make his first man like all the rest to follow? Would God, in other words, not create with the appearance of pre-existence? ★
so often cited as a premier example of reason at its most perfectly and preciously ridiculous
reasonの意味がよくとれません。しばしばその最も完全な極めてばかげたことにおいて、理由の？（理性の？）第一の例として引用される・・・？
2） Since Omphalos is such spectacular nonsense, readers may rightly ask why I choose to discuss it at all.
この英文の最後のat allはどのように訳すのでしょうか？
オムファロスはそのように目覚ましいばかげた考えであるので、読者はなぜ私がそれを議論することを選ぶのか当然のことながら尋ねるかもしれません。
(at allをどこにどのように入れて訳したらよいのかがわかりません）
3) Any honest passion merits our attention, if only for the oldest of stated reasons
if only～がわかりません。いかなる誠実な情熱も私たちの注目に値します。定まった理由の最も古いものにとって・・・・？
エッセイの一部分なので、大変わかりにくい文だと思いますが、よろしくお願いいたします。
