So as to not clutter the IC thread...<br/><br/>http://www.d20pfsrd.com/magic#TOC-Preparing-Wizard-Spells<br/><div class="quoteheader"><div class="topslice_quote">Quote</div></div><blockquote class="bbc_standard_quote">Spell Preparation Time<br/><br/>After resting, a wizard must study his spellbook to prepare any spells that day. If he wants to prepare all his spells, the process takes 1 hour. <strong>Preparing some smaller portion of his daily capacity takes a proportionally smaller amount of time, but always at least 15 minutes, the minimum time required to achieve the proper mental state.</strong><br/><br/>Spell Selection and Preparation<br/><br/><br/>Until he prepares spells from his spellbook, the only spells a wizard has available to cast are the ones that he already had prepared from the previous day and has not yet used. During the study period, he chooses which spells to prepare. If a wizard already has spells prepared (from the previous day) that he has not cast, she can abandon some or all of them to make room for new spells.<br/><br/>When preparing spells for the day, a wizard can leave some of these spell slots open. <strong>Later during that day, he can repeat the preparation process as often as he likes, time and circumstances permitting.</strong> During these extra sessions of preparation, the wizard can fill these unused spell slots. He cannot, however, abandon a previously prepared spell to replace it with another one or fill a slot that is empty because he has cast a spell in the meantime. That sort of preparation requires a mind fresh from rest. <strong>Like the first session of the day, this preparation takes at least 15 minutes, and it takes longer if the wizard prepares more than one-quarter of his spells.</strong></blockquote><div class="quotefooter"><div class="botslice_quote"></div></div><br/>It does say "Wizard," but wizards were the only prepared arcane caster when the text was written  :-)<br/><br/>