Pronounced Koo-hoo-lin, Cu Chulainn is a semi-divine figure born to the god Lugh and mortal mother Deichtine. He is the husband to Emer though he was said to have a number of wives.
Also known as the Hound of Ulster, he is arguably the greatest warrior of all Celtic lore. Born as Setanta, which means the knower of ways, his mother fosters him to the king of Ulster. Some traditions suggest that the boy had seven foster fathers who provided for him in a variety of ways, not only in material comfort but by giving him training in poetry eloquence and other skills. When he was 7 years old he arrived late to a feast being held by the smith Culann and found the smith's hound standing guard. When the dog attacked him he promptly killed it. Although unharmed, Culann was distressed since his guard dog was now dead. The young Setanta gallantly offered to raise another hound and train it, but until then would serve as Culann's "hound'. This is how he got his adult name Cu Chulainn meaning "hound of Culann" and may also be the source of his most important geis, or sacred injunction, never to eat the flesh of a dog.
He is also known for his battle frenzy. While striving to win Emer's hand, he fought and killed three hostile warriors known as the Sons of Nechtan. During this battle, he experienced the terrifying shift in both his consciousness and physical appearance called the riastradh - the battle frenzy. The description of it is quite amazing: his body twisted about within his skin, his lips peeled back from his mouth revealing the bone around the teeth, one eye sank deep within his skull while the other fell out of its socket, his heart boomed as loud as a kettledrum and a spout of blood gushed geyserlike from a hole in the crown of his head. Once in this state, he could kill 40 people with a single blow. It was apparently so dangerous that once he entered it no one, not even friends or comrades, were safe. One story tells of him approaching Emain Macha in this state and the alarmed king sent the women of Ulster out to greet him - naked. This is what it took to startle and distract him enough that the Ulstermen could grab him. However still his rage continued and they had to dump him in three vats of cold water, the first of which exploded and the second boiled over, before he finally snapped out of it.
So what spiritual lesson can be learned from Cu Chulainn? It may be related to Theodore Roosevelt's advice: "Speak softly and carry a big stick". A warrior achieves nothing by being only somewhat frightening. It is often difficult to integrate the spirit of a warrior with the path of inner wisdom, but in truth we cannot be just peacemakers without also bieng capable of defending our boundaries and fighting for what is right.
Cu Chulainn reminds us of all that is great and noble about the warrior's ideal, but also stands as a warning of the consequences of that ideal taken to an extreme out-of-balance. We definitely honor him when we take a stand or fight for what's right but we also honor him when we lay down our weapons or when we choose to make love, not war. He reminds us that the line that seperates "pushing the limits" from "going over the edge" is very thin. When you choose to work with his energy, always be mindful of that line.
The best time of year for honoring this great and tragic hero would be either Lughnasadh, a day sacred to his father, or Samhain.