diff --git a/04_ndl_and_semantics/src/summary.txt b/04_ndl_and_semantics/src/summary.txt
index 70cdccc..19914e0 100644
--- a/04_ndl_and_semantics/src/summary.txt
+++ b/04_ndl_and_semantics/src/summary.txt
@@ -18,3 +18,29 @@
   * speaking is public affair
   * Descartes started with lonely self with only it's own sensations
     * Wittenstein want's to overturn this old model and start with the culture.
+
+# Bertrand Russel
+
+* Wittgenstein was his protege
+* Co-Founder of analytic philosophy
+* theory of descriptions
+  * about wheter a sentence like 'the current king of france is gray' is true, false or meaningless
+  * he says it means: one king of france exists and he is gray.
+  * so there can't be empty identities
+    * if no king of france exists, the sentence is simply false
+* Links:
+  * https://en.wikipedia.org/wiki/Bertrand_Russell%27s_views_on_philosophy#Philosophy_of_language
+  * https://en.wikipedia.org/wiki/Bertrand_Russell
+  * https://en.wikipedia.org/wiki/Theory_of_descriptions
+
+# Early Wittgenstein
+
+* Student and Friend of Russel
+* early work named The Tractatus
+* a simple statement pictures a state of affairs (Sachlage) about simple objects
+* a simple statement is true if state of affairs exists
+* complex statements are with *and*, *or* and *not* compound simple statements
+* statements which not fit in this are nonsensical
+* most philosophical views are nonsensical
+* Link
+  * http://www.harryhiker.com/ap/witt--00.htm