Spencer is a historian who knows whereof he speaks.
I've met a few in my day, so I know whereof I speak.
Michnik knows whereof he speaks and writes, unlike so many of those in the European media who are busy gnawing at the supports of the trans-Atlantic alliance.
Sharon Leach wrote in the Sunday Observer of the agonies of having to do without water, and she knows whereof she speaks.
It's full of the stuff that packs the dance floor: a defiant but dignified message of survival sung by a woman who knows whereof she speaks.
Because, and believe me I know whereof I speak, the world is "full" of people who think they have the right to be obnoxious about your parenting choices.
When Chinese dissenters claim that Chinese socialism is a form of feudalism they know whereof they speak.
Talab al-Sana'i, an Arab member of the Israeli Knesset, is one of Amayrah's key sources, and it seems likely to me that he knows whereof he speaks.
UN envoy to Iraq Lakhdar Brahimi knows whereof he speaks when it comes to civil war.
I know whereof I speak