Read: John 10:1-18
Sheep are essentially helpless and as domesticated animals go, sheep are honestly pretty much the most helpless.
For instance, sheep can spend their entire day grazing in the pasture, going from place to place, never looking up causing them to often become lost.
In contrast, if you have a cat or dog that gets out of the house, what do they typically do? (besides run around) They typically eventually try to find their way home.
Sheep on the other hand don’t have this instinct like other animals do. They are totally incapable of finding their way to their sheep pen / fold even when it is in plain sight.
Sheep are also very susceptible to injury and cannot defend themselves against predators such as wolves. In ancient times and even today, wolves were/are the main predators of flocks of sheep.
Another interesting fact is that if different flocks of sheep somehow get mixed together at a watering hole or somewhere, the only way to separate the flock would be for a shepherd to call out to his sheep. Then, even as helpless and inattentive they are as animals, they would hear and recognize the shepherd's voice and follow him out amongst the other flocks.
The sheep knew the voice of the shepherd and the shepherd knew his sheep.
The shepherd was their safety and a true shepherd would go to great lengths to protect them when faced with danger, even giving their lives for the sake of the flock.
Shepherds were the providers, guides and protectors of the sheep and the sheep were completely dependent on the shepherd.
