From Myli I went a good half hour to the Lernaean Cave. At the foot of the rocks, in which the cave is situated a few lr. above, the spring of the Cephalarius comes forth with beautiful clear water, and so abundantly that at its outflow it forms a broad stream, which drives several mills further downstream, two of which belong to the state and are to be used to set up powder manufacture there, as this place lies lonely, so that no harm can be done in such a case because of the frequent flying up of all the powder mills in the vicinity.
Pausanias VII. 37.4. reports the following about the Lernaean snake: "At the spring Araymone a plane tree has grown up; under this plane tree the water snake is said to have fed. I believe that this animal differed in size from the other water snakes, and that its poison was so incurable that Heracles could poison the tips of his arrows with its slobber. But it seems to me that it had only one head, not several. Peisandros, on the other hand, the Kamirean, in order that the beast might appear all the more terrible, and so that his poetry might have more meaning, attributed several heads to this serpent."
Very close under the cave now leads the new artificial road to Tripoli; a few lr. up is the entrance to the cave, in front of which lies a mighty fallen piece of rock, on the side on which one enters; a dark, high, long room opens and hundreds of bats fly around the head of the disturber of the peace in the chiaroscuro. This cave was formed by the collapse of lower limestone banks, to which the stream gushing out at the foot contributed; it receives some daylight through that piece of rock, it is probably the one that Heracles rolled onto the immortal head of the serpent. According to the myth, he found it in the cave and is said to have hunted the monster down from his camp with arrows.
It is worth the effort to visit this cave, it resembles a large long rock hall and makes more of an impression in the semi-darkness, as it is in full day, than the caves of this kind, e.g. the one on the Pentelikon. If you add to this the Hydra with 50 heads, swollen with poison here in the gloomy lair as a ghastly lump, the cave, which is entirely suitable for it, gains even more interest.
A large water snake must have once lived in the cool cave, and the bigger it grew, the more it needed to feed, which is why it had to attack the herds and became a terror to the area like a lindworm. A large sea crab, which Hera sent to help the Hydra and pinch Heracles' feet, may also have lived in the nearby spring. In the time of the myths, the lands were still sparsely inhabited and animals could grow large and terrible, which in later times were destroyed when they were still young. In the same way, it is not at all miraculous and improbable that lions from Asia strayed into Greece; furthermore, there were bears in Greece at Parnes and elsewhere, which are now extinct.
It is therefore not necessary to take this myth as an allegorical image: the spring that sinks the land towards the sea branches 50 times, this is the Hydra. This swamp was never dangerous and feared, it has too much vegetation and is one of the most harmless in the country, it still exists today, so it would not be true at all that Heracles conquered the Hydra, and the chopped-off heads could not grow again, posterity says nothing about that.
In general, it is probably the most natural thing to imagine among the gods and heroes of the most distant antiquity excellent men whose useful or harmful deeds have been magnified and embellished with poetic sense by contemporaries and even more so by posterity; man's imagination loves the marvellous. If the heroes of mythical times were only air and mist, how could they be condensed into bones, weapons, etc., which one finds in their tombs, e.g. in the tomb of Achilles at Troy, and would find in others if one were allowed to open them or knew where they are.
The limestone of the Lernaean cave is dense, yellowish-grey and intergrown with many white calcareous spathes; the dense parts of the limestone are often interspersed with delicate black layers; the somewhat thicker ones separate easily because they contain a black slaty clayey mass.