One of the earliest proofs of G.R. was the deflection of light by a gravitational field, first shown in 1919 during a solar eclipse.

I think Einstein predicted approximately 1.7 seconds of arc deflection during that eclipse. But in his book, Relativity (written for the general reader), Einstein says that "half of this deflection is produced by the Newtonian field of attraction of the Sun, and the other half by the geometrical curvature of space"

1) Does that mean that classical Newtonian gravitational theory would have predicted roughly 0.8 seconds of arc deflection of light, and G.R. predicts 1.7?

But wasn't light considered massless to Newton?

If so, how does Newton's gravity theory predict the attraction of light?

2) If the answer is 'no' to #1, then what does Einstein mean by the quote above?

thanks !

Paul