This is a quote from a letter printed in "Letters of Edward FitzGerald to Fanny Kemble" (Macmillan, 1902)
Feb, 1881
"I cannot doubt but that Sphinx and heaps more of the childish and dirty mythology of Greece came from Egypt, and who knows how far beyond, whether in Time or Space!"
I find that a quite extraordinary statement for 1881. As readers of my forum will know, EFG is the translator of the Rubaiyat of Omar Khyyam. Fanny Kemble is the famous American based actress, daughter of John Kemble the great Shakespearean actor. Fanny was a great campaigner for women's rights and the abolition of slavery.