diff --git a/src/cljc/mw_engine/core.clj b/src/cljc/mw_engine/core.clj
index 34e063b..97f65cf 100644
--- a/src/cljc/mw_engine/core.clj
+++ b/src/cljc/mw_engine/core.clj
@@ -22,8 +22,7 @@
             further rules can be applied to that cell."
       :author "Simon Brooke"}
  mw-engine.core
-  (:require [clojure.string :refer [starts-with?]]
-            [mw-engine.flow :refer [flow-world]]
+  (:require [mw-engine.flow :refer [flow-world]]
             [mw-engine.utils :refer [get-int-or-zero map-world rule-type]]
             [taoensso.timbre :as l]))
 
@@ -67,9 +66,17 @@
                             e
                             (.getMessage e)
                             (-> rule meta :lisp)
-                            cell))))]
+                            cell))))
+        rule-meta (meta rule)]
     (when result
-      (merge result (meta rule)))))
+      (merge result 
+             {:history (concat 
+                        (:history result) 
+                        (list {:rule (:source rule-meta) 
+                               :rule-type (:rule-type rule-meta)
+                               :generation (get-int-or-zero 
+                                            result 
+                                            :generation)}))}))))
 
 (defn- apply-rules
   "Derive a cell from this `cell` of this `world` by applying these `rules`."
@@ -84,7 +91,7 @@
          (l/warn e
                  (format
                   "Error in `apply-rules`: `%s` (%s) while executing rules on cell `%s`"
-                  e
+                  (-> e .getClass .getName)
                   (.getMessage e)
                   cell))))))
    cell))
diff --git a/src/cljc/mw_engine/utils.clj b/src/cljc/mw_engine/utils.clj
index 684064e..7a06e6f 100644
--- a/src/cljc/mw_engine/utils.clj
+++ b/src/cljc/mw_engine/utils.clj
@@ -2,8 +2,8 @@
       interpretation of MicroWorld rule."
       :author "Simon Brooke"}
  mw-engine.utils
-  (:require
-   [clojure.math.combinatorics :as combo]))
+  (:require [clojure.math.combinatorics :as combo]
+            [clojure.string :refer [join]]))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;;;
@@ -304,3 +304,43 @@
   "Return the rule-type of this compiled `rule`."
   [rule]
   (:rule-type (meta rule)))
+
+(defn history-string
+  "Return the history of this `cell` as a string for presentation to the user."
+  [cell]
+  (join "\n"
+        (map #(format "%6d: %s" (:generation %) (:rule %))
+             (:history cell))))
+
+(defn- extend-summary [summary rs rl event]
+  (str summary
+       (if rs (format "%d-%d (%d occurances): %s\n" rs
+                      (:generation event)
+                      rl
+                      (:rule event))
+           (format "%d: %s\n" (:generation event)
+                   (:rule event)))))
+
+(defn summarise-history
+  "Return, as a string, a shorter summary of the history of this cell"
+  [cell]
+  (loop [history (rest (:history cell))
+         event (first (:history cell))
+         prev nil
+         rs nil
+         rl 0
+         summary ""]
+    (cond (nil? event) (extend-summary summary rs rl prev)
+          (= (:rule event) (:rule prev)) (recur
+                                          (rest history)
+                                          (first history)
+                                          event
+                                          (or rs (:generation event))
+                                          (inc rl)
+                                          summary)
+          :else (recur (rest history)
+                       (first history)
+                       event
+                       nil
+                       0
+                       (extend-summary summary rs (inc rl) event)))))