Can a mage cast spells that they don’t have as a rote/praxis?

From what I can read in the rulebook, there are three main ways to cast a spell:

  • Improvised spells, which always have a set of general effects.
  • Rotes, which treat the highest arcanum as 5 dots for the purposes of Reach, cost no mana and allow the caster to use mudras as yantras.
  • Praxes, which also cost no mana and crit success on 3 successes.

Did I miss a part of the book that describes how to cast existing spells outside these 3 ways? If so, please point me to the right section of the book.