The text is from Quintillian's Institutio Oratoria VIII.3.ix: “Quid [illo] quincunce speciosius, qui, in quamcumque partem spectaveris, rectus est?”; roughly, “What more beautiful [way to plant trees] than the quincunx, that, from whatever direction you regard it, presents straight lines?”
This page is by James Eason.