All quotes from the Harper Perennial 2001 edition.
On runic letters:
When the Anglo-Saxons became literate in the sixth century, they took their alphabet from the Romans, but quickly realized that they had three sounds for which the Romans had no letters. These they supplied by taking three symbols from their old runic alphabet: w, ρ, and δ. The first, literally double u, represented the sound "w" as it is pronounced today. The other two represented the "th" sound: ρ (called thorn) and δ (called eth and still used in Ireland.)
(Chapter 8, page 123)
(The use of Greek characters here is a misprint.)
<w> is not runic. It was orginally a digraph formed by doubling the letter <v>. Maybe he's thinking of <ƿ> (wynn), a letter of runic origin used in Old English that was eventually replaced by <w>.
<þ> (thorn) is of runic origin.
<ð> (eth) is not runic, it's a variant of <d>. It is not used in Ireland, but it is still used in Iceland.
[I wonder why he says the Anglo-Saxons became literate when they adopted the Roman alphabet. It's true that literacy increased after the adoption of the Roman alphabet, but before that, some of them were literate in the runic alphabet.]
The richness of the English vocabulary, and the wealth of available synonyms, means that English speakers can often draw shades of distinction unavailable to non-English speakers. The French, for instance, cannot distinguish between house and home, between mind and brain, between man and gentleman, between "I wrote" and "I have written."
(Chapter 1, page 13)
According to my Concise Oxford French-English Dictionary:
house: la maison
home: la demeure
brain: la cervelle
gentleman: le monsieur
It's true that j'ai écrit can mean both "I wrote" and "I have written", but it's a bit more complicated than that. French has two other forms for "I wrote":
l'imparfait: j'écrivais ("I wrote him a letter every day for five years")
le passé simple: j'écrivis (used instead of j'ai écrit in written French)
And for the "past action with present relevance" sense of the English past perfect, French can use the passé récent: je viens d'écrire means "I have just finished writing (a letter)".
A second commonly cited factor in setting English apart from other languages is its flexibility... where the Germans can just say "ich singe" and the French must manage with "je chante," we can say "I sing," "I do sing," or "I am singing."
I am singing: je suis en train de chanter
I do sing: je chante vraiment
It's not that French does not distinguish between "I wrote" and "I have written" or between "I sing" and "I am singing," it's that it makes the distinctions in different ways than English does.
English, as Charlton Laird has noted, is the only language that has, or needs, books of synonyms like Roget's Thesaurus. "Most speakers of other language are not aware that such books exist." [The Miracle of Language, page 54]
The Eskimos, as is well known, have fifty words for types of snow - though curiously no word for just plain snow. To them there is crunchy snow, soft snow, fresh snow and old snow, but no word that just means snow.
Some cultures don't swear at all. The Japanese, Malayans, and most Polynesians and American Indians do not have native swear words. The Finns, lacking the sorts of words you need to describe your feelings when you stub your toe getting up to answer a wrong number at 2:00 AM, rather oddly adopted the word ravintolassa. It means "in the restaurant".