In the fourth book of Homer's Odyssey, Odysseus' son Telemachus travels to Sparta in search of news about his father. He goes to the palace of Menelaus and Helen, the king and queen of Sparta, and questions them about Odysseus.
Before Menelaus begins a full account of his adventures, Helen
"thought to slip a drug into the wine they drank, one that calmed all pain and trouble, and brought forgetfulness of every evil. Whoever tasted it mixed with the wine would shed no tears that day, not though his mother and father lay there dead, not though they put his dear son or his brother to the sword, before his very eyes" (A.S. Kline translation).
Helen then goes on to recall her own encounter with Odysseus at Troy. She recalls how Odysseus had disguised himself as a beggar, infiltratred Troy, killed a number of Trojans, and gathered much key information before returning to the Greek camp. Helen also notes that she had seen through Odysseus' disguise and had provided him with some assistance.
Menelaus also recalls that when the Greeks were hiding in the wooden horse, that Helen had imitated the voices of the Greeks' wives. Some of the Greeks wanted to call out, but Odysseus prevented them from doing so.
Thus, in this passage we learn of Odysseus' cunning ways and how he is a master of the cerebral side of war.