The untranslated bit on page 16 actually explains a lot about the difference between "inherent" and "acquired" magic. It says "2+3 is 2+3. ...10÷2?? Huh? What's that?". Basically, "acquired" magic is parroted magic; you say the formula, a thing happens, but you don't understand the formula. You can't analyze it. Meanwhile, "inherent" magic realizes that 2+3=5, 5=10÷2, so 2+3 = 10÷2. They can analyze what they're doing, try substituting in equivalents, and thus modify what they're casting.
Fun fact: arithmetic is the study of numbers (and that thing you do with numbers, counting). All the functions of arithmetic (+-x÷^) can be done by counting. Algebra, however, flexes the power of =, >, and <, letting you solve problems that arithmetic can't handle.
...on the off chance anyone happened to be wondering... ¬_¬
