diff --git a/book/source/04-certificates.md b/book/source/04-certificates.md
index a89d21d..e0ddfaf 100644
--- a/book/source/04-certificates.md
+++ b/book/source/04-certificates.md
@@ -212,7 +212,7 @@ OpenPGP has a lot of ["cryptographic agility"](https://en.wikipedia.org/wiki/Cry
 
 This agility has the advantage that adoption of new cryptographic primitives into the standard is relatively easy, and can be done without disruption. Users can gradually migrate to using new cryptographic mechanisms.
 
-However, it also means that OpenPGP software needs to figure out which mechanisms a set of communication partners can handle and prefers. To do this, there are a number of mechanisms in OpenPGP that can be negotiated between sender and recipient. The sender interprets the preferences of the recipient:
+However, it also means that OpenPGP software needs to figure out which mechanisms a set of communication partners can handle and prefer. To do this, there are a number of mechanisms in OpenPGP that can be negotiated between sender and recipient. Note that OpenPGP is not an online scheme, so this negotiation is effectively one-way: The active party interprets the preferences that are expressed in the certificate of the passive party.
 
 - [Preferred Hash Algorithms](https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-12.html#preferred-hashes-subpacket)
 - [Preferred Symmetric Ciphers for v1 SEIPD](https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-12.html#preferred-v1-seipd)