[squirt]

Yes and yes!

It's due to the way penmanship was written. Consider the arm position [0] of proper penmanship. The page is at an angle to the left, such that it is similar to the angle of your forearm on the page. Pivoting at the elbow allows you to swing your arm from the left side of the page to the right. The forward slant allows you to always be moving "forwards" as you write across the page.

I hope that was clear. Please feel free to ask clarifying questions if not.

[0] https://archive.org/details/armmovementmetho00zane/page/12/m...

[yodon]

I agree that the slant is intentional, but it's not clear to me that the slant comes as a result of the preferred arm position (it seems equally likely the arm position was chosen because it results in the desired slant).

As you might be aware, arm position and use in serious calligraphy is a far more thoughtfully and intentionally designed process than I ever would have imagined. A major component of Spencerian technique involves resting the right forearm on the left palm (I think I have that right, I'm not actually one who does Spencerian writing) in order to use the flesh of the forearm as a linear bearing driven by the shoulder muscles and constrained by the left palm as a means of achieving a more repeatable and predictable translation motion than can be achieved with simple proprioception based motor control.