「新々英文解釈研究」の最初の方に出てくる、”He is an oyster of a man.”の出典と思われるものを突き止めました。（OEDでのoysterやclamで「寡黙な人、非社交的な人」という意味の用例がマーク・トウェインが多かったので、最初マーク・トウェインの何かの作品かと思って、マーク・トウェイン作品のテキストが検索出来るページで調べましたが見つかりませんでした。）John Dunlopというスコットランドの詩人（1755 ｰ 1820）の書いた歌詞の中に”an oyster of a man”が出てきます。しかし、これは1812年の「ジョージ・マッカルがグラスゴーの『牡蠣クラブ』から引退するにあたって」という歌であり、かなり特殊な文脈で使われていることが確認出来ます。しかもおそらく、ジョージ・マッカルという人は何らかの理由で、「牡蠣クラブ」から引退（または退職）するのであり、そこで「牡蠣のような人」というのは「牡蠣クラブを象徴するような人（または常連客、あるいは従業員）」という意味でほとんどジョーク的に使っていると考えられ、「寡黙な人」という意味ではないように思います。歌詞の中に「白鳥のように自分自身のレクイエムを歌う」とありますから、ますます無口であるという解釈はおかしいです。それに「牡蠣クラブ」はおそらく美味しい牡蠣を食べながら社交を楽しむ人の会かあるいはオイスター・バーの名前ではないかと推察されます（現在でも同名のオイスター・バーが各地にあります）ので、まったくもって「寡黙な人」はおかしいと思います。ちなみに、歌詞の中の”Tiny Lochrians ! huge Pandores !”はどちらも牡蠣の品種だと思います。（前者はOEDに載っていませんが多分「Ryan湖(Loch Ryan、塩水湖）の牡蠣」ということだと思います。18世紀の始めから牡蠣の養殖場で有名のようです。後者は”A kind of large oyster found in the River Forth, esp. near Prestonpans.”とあります。）ジョージ・マッカルは、そういう色んな牡蠣に愛される人間だけど牡蠣みたいな人、って言っているんでしょうね。調べてみたらスコットランドのグラスゴーは今でも牡蠣で有名で色んなオイスター・バーやレストランがあり、そういう町で「牡蠣のような人」というのがネガティブな意味では決してないと思います。

John Dunlop (writer)
https://en.wikipedia.org/wiki/John_Dunlop_(writer)

“Dunlop of that ilk : memorabilia of the families of Dunlop … ; with the whole of the Songs ; and a large selection from the poems of John Dunlop”

ON GEORGE M’CALL RETIRING FROM THE “OYSTER
CLUB” IN GLASGOW (1812).

[His letter of demission ended with four verses wretched poetical lines.]

The Oyster Club, in sable clad,

Laments for George M’Call,
Who, swan-like, his own requiem sings.

Weep ! Weep ! ! ye oysters all.
Tiny Lochrians ! huge Pandores !

Forget him, if you can ;
He was, creation must confess,

An oyster of a man ! !

拙試訳
牡蠣クラブ、喪服を着て
ジョージ・マッカル氏を悼む
氏は、白鳥のように、自分自身のレクイエムを歌う
ああ悲しい、悲しい、牡蠣のみんなよ
小さなリャン湖の牡蠣、大きなパンドレス牡蠣よ
もし可能なら彼を忘れよう
氏は、創造主は告白しなければならないが、
まさに人間牡蠣だった。

The following essay is what I wrote as an assignment for a writing course at an English school AEON:

Topic: Festivals
Style: Casual

I would like to introduce a famous festival held during the so-called golden week in Shimonoseki city, my birthplace. The name of the festival is Senteisai (a festival for the passed emperor) held from May 2 to May 4. The purpose of the festival is to pacify the spirit of the emperor Antoku who died young in 1185.
In late 12th century Japan, two dominant samurai families, Genji and Heike fought each other trying to get the governance of Japan. The battle of Dannoura was the last one where Genji defeated Heike completely on the Kanmon channel. It was a naval battle where many ships of the both sides fought on a very narrow channel called Kanmon channel between Honshu and Kyushu. In the first stage of the battle, Heike had superiority, but because of the change of tide, Genji finally destroyed most ships of Heike. The emperor Antoku, who was a grandson of Kiyomori Taira of the Heikes and was just 6 years old at the battle, was getting on a ship with some female retainers. Most remaining samurai and retainers drowned themselves. The young emperor asked to a female retainer where they would go. She replied that they would go to the paradise and there was another metropolis at the bottom of the sea. Then, she brought him into the sea.
Some menials were drawn up from the sea and survived. Many of them were forced to do prostitution to make a living. Later they started to hold a festival to comfort the spirit of the late emperor. That was the start of Senteisai. The most spectacle attraction on the festival is a parade of beautifully attired geisha girls called “joro dochu”. (Joro is another name of geisha in Japanese.)
It is alleged and also believed that it surely rains on at least one day among the three. We call it the tears of Heike people.
Lafcadio Hearn, aka Yakumo Koizumi in Japan, wrote a story of Miminashi Hoichi (Hoichi the earless). Hoichi was blind and was a story teller of the battels between Genji and Heike, accompanied by the biwa, a Japanese lute. He was favored by some ghosts of Heike. Whenever he told the story to them, all the ghosts cried harshly at the scene of the death of the young emperor. A famous priest tried to save his life and wrote holy scripts of Buddhism on all parts of his body. But because the priest failed to write them on Hoichi’s ears, his ears were found and taken by the ghosts. He survived, but later he was called Miminashi Hoichi, Hoichi the earless.