And, no, it’s not “Milton the Monster,” but John Milton:
“Truth never comes into the world but like a bastard, to the ignominy
of him that brought her birth.”
Is this just a quote, or is it one of his works?
According to an old copy of George Seldes’ compilation “The Great Quotations,” the quote is from * A Complete Collection of the Historical, Political, and Miscellaneous Works of John Milton. *
This suggests that it’s likely not from another specific work, although that would be accurate only to the extent Seldes is accurate in the compilation.
The complete original document you are looking for (a published open letter to Parliament) can be found at the Dartmouth on-line reading room for Milton.
I hope this meets your needs.