diff --git a/notsof.md b/notsof.md
index 2346afc12..3ebc88110 100644
--- a/notsof.md
+++ b/notsof.md
@@ -77,7 +77,10 @@
 - two ways to describe [[form]]:
   - [[formal]], what it "is"
   - [[functional]], what it "does"
-  - a unified description is the abstract equivalent of a constructive diagram
+- a unified description is the abstract equivalent of a constructive diagram
+  - a constructive diagram can often *precede* the knowledge which explains its shape
+  - [[aside]]
+    - [[visual cortex]], [[eric weinstein]]