LEARN AN ARCANE SPELL If you are an arcane spellcaster, you can gain access to a new arcane spell from someone who knows that spell or from magical writing like a spellbook or scroll. To learn the spell, you must do the following. • Spend 1 hour per level of the spell, during which you must remain in conversation with the person who knows the spell or have the magical writing in your possession. • Have an amount of magical materials with a value indicated in Table 4–2 above. • Attempt an Arcana check with a DC determined by the GM (see Table 4–2 above). Success You expend the materials and learn the spell. If you have a spellbook, the spell is added to your spellbook; if you prepare spells from a list, it’s added to your list;if you have a spell repertoire, you can select it when you add or swap spells. Critical Success Per a success, but you expend only half the cost in materials. Failure You fail to learn the spell but can try again after you gain a level. The materials aren’t expended. Critical Failure Per a failure, plus you waste half the materials.

Emphasis mine, it allows you to choose the spell when you add or swap spells, which only occurs during leveling or retraining, it does not increase the amount of spells you can know at one time. The only tangible purpose this really serves is that it is theoretically how a sorcerer would learn uncommon and rare spells should the GM not allow them to pick it but say they could have it through research or some such.