diff --git a/posts/ideas.md b/posts/ideas.md
index 2383c96f..7266e85d 100644
--- a/posts/ideas.md
+++ b/posts/ideas.md
@@ -31,7 +31,7 @@ This insight has many implications. If you are trying to come up with good tacti
 
 Here, “queen = 9 pawns, rook = 5 pawns, knight = bishop = 3 pawns” functions as a **generator** of further downstream ideas: it’s an insight that you can start with that is much more likely to generate effective tactics than searching completely randomly. We can think of that statement as being an "ideology". Since pieces on the board in chess are called [material](https://www.chessstrategyonline.com/content/tutorials/basic-chess-concepts-material), let us overload an [already-overloaded term](https://en.wikipedia.org/wiki/Materialism_\(disambiguation\)) and call this ideology “_materialism_”.
 
-One could imagine someone who disagrees with materialism, either partially or fully. Often, sacrificing material is okay in service of _positional_ goals, such as exposing the opponent’s king or claiming the center of the board. The value of material can also be context-dependent. In an endgame, I’ve found that single knight is worth more than a single bishop, whereas two bishops are worth more than two knights. If your opponent has one bishop left, pawns might be worth more if they are on squares of the opposite color to that bishop. A person whose approach to chess tactics focuses on exploiting these situations might call themselves a “_positionist_”.
+One could imagine someone who disagrees with materialism, either partially or fully. Often, sacrificing material is okay in service of _positional_ goals, such as exposing the opponent’s king or claiming the center of the board. The value of material can also be context-dependent. In an endgame, I’ve found that a single knight is worth more than a single bishop, whereas two bishops are worth more than two knights. If your opponent has one bishop left, pawns might be worth more if they are on squares of the opposite color to that bishop. A person whose approach to chess tactics focuses on exploiting these situations might call themselves a “_positionist_”.
 
 Positionists and materialists may disagree on practical issues, such as whether or not to trade two pawns for a bishop in a situation like this: