Temperament:

A working dog's behavior is key in training the dog to be the best it can be.
Temperament is at the top of the heap, because it affects every area of of a dog’s life and work. The reason dogs sometimes have behavioral problems is that there isn’t enough emphasis put on temperament. Many people think they can breed a dog, skip some steps along the line and they still expect to reap the benefits from a productive working dog. To get the proper ability out of working dog there are steps from training the dog from been often weak, timid or tense to training the dog to be stronger and calmer with ability and strength.
People fail training dogs because you cannot seperate temperament from ability in this way. The timid, soft, or tense dog’s temperament is what will cause it to work in a way that it does become cautious and strong eyed. The thing is if you changed it’s temperament you would change it’s work simultaneously. Work and temperament are inseparable. This is why controlling the temperament in your working dog is at the top of the list of steps to follow. The key factor is that you cannot have dog with a poor temperament that will be a good performer as a working dog. It’s as simple and plain as that!
A good temperament:
So, what is a good temperament? Put in easy to understand terms it is for the dog to be calm and bold. These are the main things to look for. You can see this in young pups long before they go anywhere near sheep.

A good sheep herding dog has have a mix of good Temperament and Intelligence to be successful.
Intelligence:
Intelligence is a valuable trait, but the amount of ‘brains’ a dog shows in it’s work is more dependant on it;s working instincts, and temperament,

Dogs Herding sheep.
than on it’s intelligence alone. For example, an excitable or busy dog, or one with too much ‘eye’ or too keen on the head, will not think about what it is doing no matter how intelligent it may be.
Even when just taking pups for a walk you can see how their temperament affects their ability to use their intelligence. If you climb through a fence ], the calmer pups will generally find a way through after you, whereas those with poorer temperaments will often yelp and run backwards and forwards. It isn’t that they are necessarily less intelligent, but that their temperament doesn’t allow them to USE their intelligence.
The plus side of a intelligent dog is that it learns fast and turns into a better dog (along with guidance from the handler of course). This been said the dog can also learn bad habits faster than less intelligent dogs and then act up.