Cf. Milton, Paradise Regained, iv. 244:—
See there the olive-grove of Academe,
Plato's retirement, where the Attic bird
Trills her thick-warbled notes the summer long.
Perhaps the idea of Ilissus bending over the urn is taken from the western pediment of the Parthenon. At one angle there is a recumbent figure of the Kephissus, at the other of the llissus; originally there seems to have been a ὑδρια attached to one of them. See Guide to Sculptures of the Parthenon, published at the British Museum.[CB]
And, following guides whose craft holds no consent
With aught that breathes the ethereal element,
Hath stained the robes of civil power with blood,
Unjustly shed, though for the public good.