I'm sorry if this question is too basic (I'm really impressed with the learned people answering questions on Mi Yodeya!).
I was reading about the Council of Jamnia on Wikipedia:
And I came across this:
Jewish sources contain echoes of debate about biblical books but canonicity was not the issue and debate was not connected with Jabneh... Moreover, specific canonical discussion at Jabneh is attested only for Chronicles and Song of Songs. Both circulated prior to Jabneh. There was vigorous debate between Beth Shammai and Beth Hillel over Chronicles and Song; Beth Hillel affirmed that both "defile the hands." One text does speak of official action at Jabneh. It gives a blanket statement that
"all Holy Scripture defile the hands,"
and adds "on the day they made R. Eleazar b. Azariah head of the college, the Song of Songs and Koheleth (Ecclesiastes) both render the hands unclean" (M. Yadayim 3.5).
Can someone explain to me what is meant by "all Holy Scripture defile the hands"?