diff --git a/contributing.md b/contributing.md
index f716665662..8723d23d54 100644
--- a/contributing.md
+++ b/contributing.md
@@ -21,4 +21,6 @@ Truths which we believe to be self-evident:
 1. **It's an asynchronous world.**  Be wary of anything that is
    anti-asynchronous: ACKs, protocol confirmations, or any protocol-level
    "advisory" message.
+1. **There is no such thing as time.** Protocol ideas that require synchronized
+   clocks are doomed to failure.