Before, dark and opaque bodies had surrounded me, impervious to my touch or sight; but I now found that I could wander on at liberty, with no obstacles which I could not either surmount or avoid. The light became more and more oppressive to me; and, the heat wearying me as I walked, I sought a place where I could receive shade.

In Chapter 11, near the start of the monster’s long account to Victor of his activities after leaving Victor’s apartment in Ingolstadt, he describes his first encounter with sunlight, which is a highly symbolic element in the book. You can read more about the significance of this quote in Quotes by Symbol: Light and Fire.

I was a poor, helpless, miserable wretch; I knew, and could distinguish, nothing; but feeling pain invade me on all sides, I sat down and wept.

The monster speaks these words in Chapter 11 to describe the sensations he felt shortly after being brought to life and abandoned by Victor. At this point, he is entirely new to the world, and he doesn't understand how to protect himself from the cold or how to find food other than berries. He feels completely isolated and entirely helpless, like a child who has been thrown into the woods and now must fend for himself. Because Victor ran from him instead of embracing him, the monster's first feelings are pain, misery, and confusion, instead of safety, acceptance, and curiosity, and this profoundly affects how he understands and interacts with the world.

One day, when I was oppressed by cold, I found a fire which had been left by some wandering beggars, and was overcome with delight at the warmth I experienced from it. In my joy I thrust my hand into the live embers, but quickly drew it out again with a cry of pain. How strange, I thought, that the same cause should produce such opposite effects!

Fire is an important symbol in Frankenstein, a powerful and dangerous element that the monster is both attracted to and intimidated by. In Chapter 11 he describes his first interaction with fire, which initially causes him delight but seconds later causes him pain; its warmth comforts him, but its burn teaches him that a source of good can also cause harm. This lesson reocurrs when he interacts with humans: he longs for the warmth of love and connection, but instead encounters pain from their rejection and cruelty. You can rad more about this quote in Quotes by Symbol: Light and Fire (the second quote for Chapter 11).

The whole village was roused; some fled, some attacked me, until, grievously bruised by stones and many other kinds of missile weapons, I escaped to the open country and fearfully took refuge in a low hovel, quite bare, and making a wretched appearance after the palaces I had beheld in the village. This hovel however, joined a cottage of a neat and pleasant appearance, but after my late dearly bought experience, I dared not enter it. My place of refuge was constructed of wood, but so low that I could with difficulty sit upright in it. No wood, however, was placed on the earth, which formed the floor, but it was dry; and although the wind entered it by innumerable chinks, I found it an agreeable asylum from the snow and rain. 

Here, then, I retreated and lay down happy to have found a shelter, however miserable, from the inclemency of the season, and still more from the barbarity of man.

Later in Chapter 11, the monster describes being driven away by the hostile villagers and his retreat back into isolation. The explanation of this quote in Quotes by Setting: Europe equates the monster’s forced isolation to the dark, isolated room where Victor chose to dwell in Ingolstadt.