It depends on your Intelligence score (work with your GM)
This answer is based on the 4th printing, Swords and Wizardry, Core Rules, 2011.
On page 7, the chance to learn a given spell is laid out in a table. I'll use three examples. Int of 13, Int of 15, and an Int of 17 as well as referring only to the columns in that table for the Int score, the % chance to know a spell, and the Min/Max number of spells per level you can know.
| Int Score |
% Chance to Know |
Min/Max Known |
| 13 |
65 |
5/8 |
| 15 |
75 |
6/10 |
| 17 |
85 |
7/All |
At first level, you consult the list of first level spells on page 46. There are 8 of them.
Charm Person, Detect Magic, Hold Portal, Light, Magic Missile, Protection from Evil, Read Languages, Read Magic, Shield, Sleep.
- What we did in old school games was start at the top of the
list and work down, checking by rolling precentile dice. (It was the simplest way). We did have one DM who had us indicate which spells we wanted, and we'd check spell by spell to see if we knew it or not. Either way works.
You check for each spell: roll your percentile dice; each time you roll 65 or less, you know that spell. If all 8 of your rolls are 65 or less, you know all of them. Also, you know No Less Than 5. So if you fail 4 rolls, check again on the failed spells until you get that fifth one, or choose one: work with your GM on that.
If your Int was 15, you have a 75% chance to know each spell and have no less than 6 in your book.
With a 17, you have no less than seven, and perhaps all, depending on your luck with the percentile dice where the target is 85% or less.
Conversely, if your intelligence score is 11, you can start with at most six of those spells in your book.
As you go up in levels, you'll make those checks again for spells of higher levels. Or you won't. ;)
Working with your GM is an expected part of this game style
You will see on page 7 where it is written that "the author doesn't use that rule."
This means ask your GM: is there a reason to not know all eight? If not, then all eight spells are in your book.
See the introduction by Tim Kask on page 4, where he speaks to GM's.
What you hold in your hand are guidelines; this is one set of “rules” that has an internal integrity that makes it work. Is it the only way to play? Certainly not; from the very beginning of role-playing GMs have been encouraged to extrapolate and interpret, to make the game their own. If a given rule does not seem “right” to you, then ignore it! Or, better still, change it! Make your game or campaign your own. All GMs need to worry about is keeping a “logical reality” active in their campaigns; the players rely on that logic to find their way through the perils and puzzles of the adventure.
