This book explains how all the letters can be made gracefully and rapidly using various combinations of a few basic pen strokes. It explains Spencer's philosophy of teaching principles which engage the mind as well as the hand. It also details his methods for teaching classes of children. One of these is having the children write rhythmically, in concert, as the teacher counts. The power of this method is being rediscovered today.
Platt Rogers Spencer (also Platt R. Spencer) was the originator of Spencerian penmanship, a popular system of cursive handwriting. He was a teacher and active in the business school movement.
A great step by step guide along all the ins and outs. I personally did use it alongside other youtube resources to see people's hand in motion and highly recommend that for specific actions, it just really was that last step every time for my muscles to get it right.
That aside, there's a few variations I've seen for letters being used so I suppose you just have to keep that in mind and choose what style you prefer. This book is filled with wonderful exercises that get you used to all sorts of little details you need to get your hand conditioned into being comfortable doing for the basic stuff as well as the more artful style of writing.
Wishing everyone luck! Best little find on Archive.com for a hobby I've found in a while!