from "Concrete and Fastidious", a 1956 review of Njal's Saga:

I wish the translators had supplied genealogical maps and trees. I do not agree with their opinion, given in the introduction, that genealogies are boring, but for a modern reader they are easier to follow in a visual form, and, boring or not, it is impossible to follow a tale of blood-feuds without a clear knowledge of the kin relationships. The canvas in Njál’s Saga is unusually large and I would advise anyone reading it for the first time to construct his own genealogical diagrams as he goes along.

from his 1958 introduction to John Hollander's A Crackling of Thorns:

Many of Mr. Hollander’s most successful poems are songs or, at least, “words for music perhaps.” The song — the lyric is not quite the same thing — is, of all kinds of poetry, the one in which the formal verbal elements play the greatest role and are, indeed, the main source of interest. In the world of the song, one might say, the important relationship between the inhabitants is not any community of concern or action so much as family kinship. The satisfaction I get from reading a poem by Campion, for example, is similar to the satisfaction I get from studying a well worked out genealogical tree. (A wet afternoon could be pleasantly spent developing this analogy. Starting with the notion that masculine rhymes represent brothers, feminine rhymes sisters, refrains identical twins, one could ask what verbal relationship would be equivalent to a second cousin once removed. From there one could go on to consider what discords correspond to marriage within the prohibited degrees, e.g., to marrying one’s deceased wife’s sister.)