>>135It's really just from ASCII. Early on, ` and ' were symmetrical in fonts (the 8x13 fonts still display them that way), so it was the custom to use them as opening/closing quotation marks respectively. Teƒ΄ uses the convention simply because it was the obvious choice at the time. Until the universality of Unicode, it was also the only way to write quotations in a manner that nested properly. It's just the way people used to write, and is no more from anything specific than using > for quoting is. See, for example, RFC 2646.