A big hole in the ground: This is where most of the raw materials of an industrial society come from. To appreciate the scale of this excavation, note that the bright blue object on a shelf near the center of the image is a Porta Potti.
A dragline is the largest of the machines used to strip away the overburden and mine the ore layer at an open-cast mine. A bucketload for this particular dragline, one of the world's largest, is 220 cubic yards. Note the school bus, which would easily fit in the bucket.
It is related that the bodhisattva Manjusri was once standing at the gate, and seeing him, Shakyamuni Buddha called to him, "Manju, Manju, why don't you come inside the gate?"
Manjusri replied, "I don't see anything outside the gate."
When you once attain true self-realization, these barriers disappear in an instant as though they were nothing but mirages, and you will find that from the very beginning you have always been in a world where there is neither inside nor outside. That is what "gateless" means. Therefore, all koans are impassable barriers for those who are unenlightened, but for the enlightened there is no gate at all. They can come and go quite freely.
One day, as Kyogen was clearing the undergrowth, a pebble bounced off the tip of his broom and resounded against a bamboo tree. Hearing the sound, he suddenly experienced great enlightement. The first stanza of the poem he composed on this occasion is very famous:
One striking sound,
and I have forgotten all I knew.