I've just started reading Paul Mariani's Gerard Manley Hopkins: A Life (not before time - I've had it on my shelf for years). I was dubious from the start about Mariani's approach of putting himself inside Hopkins's head, telling us not just what the poet was doing on a particular date (the book is written in a series of entries, diary-style), but what he was thinking and feeling. I've always felt biographers who did this were on shaky ground, and an excellent example of why occurs in the entry for April 1866. During a stroll around Oxford, Mariani assures us, "Hopkins -- that inveterate observer of nature -- notes* the robin's-egg-blue spring sky."
I can tell you with absolute certainty that Hopkins noted no such thing. Not just because he wouldn't have used a stock phrase like "robin's egg blue," but because the European Robin -- the only robin this "inveterate observer of nature" would have been familiar with -- does not lay blue eggs. It is the American Robin (not closely related to the European Robin at all) that lays eggs of this colour, and the phrase "robin's egg blue" is American English. Mariani is American and is presumably no ornithologist; this wouldn't be a problem if he hadn't insisted on inserting his own thoughts into Hopkins's head in this silly manner.
I'll keep reading the book because of my love for its subject. I hope there won't be too many distractions of this kind.
* The book is also written in the present tense, another slight irritant.