The native black poplar is one of England's rarest trees.
The white frill is said to be the rarest, and birds exhibiting it have white necks even in winter.
The rarest of all the gulls is also found on the Peruvian coast, namely, the Xema furcatum.
Whatever other gifts Comte may have had - and he had many of the rarest kind, - poetic imagination was not among them, any more than poetic or emotional expression was among them.
The original editions of Paracelsus's works are getting less and less common; even the English versions are among the rarest of their class.