How-To/Techniques
Casting is not primarily about rod position and should not be taught “Presbyterian style” or in the 10 o'clock to 2 o'clock motions as taught in A River Runs Through It. Instead, casting is based on the principles of physics, one of them being Newton's First Law of Motion, which states that an object in motion will remain in motion. To put the line in motion you must smoothly accelerate at an exponential rate and then abruptly stop the rod.
It's vital to understand that, since fishing conditions and situations change endlessly, there can be no rigid or fixed rules or instructions for casting. You cannot specify where to start, move, or stop your arm or rod, or the direction and distance to move them, before deciding on the result you want from the cast. You must take various factors into account, including the fly being cast, the desired direction and distance, wind, any obstructions—whether overhead or to the side or rear—and more.