Iam a little bit confused by what this sentence means. (highlighted one in blue)

onto a large boat, and mark the water level that the boat sinks to. then, take the elephant out and put a bunch of marked weights onto the boat until it reaches the same water level. add up the masses of the weights to get the weight of the elephant.

1.creeping like a snail is a simile used in this poem and it means the child is going to school unwillingly./a child is unwilling to go to school.

2. man becomes very frail and loses his physical strength when he becomes old, so much that his leggings that used to fit him snugly when he was in his youth are now too loose for him to wear, and that his shank has shrunk so much that this worldly stage is too big for a feeble actor like him. although, 'his youthful hose' just refers to his leggings/pants/ to shrink from danger; to shrink from contact.

3.the words "sans" means "without." it is a french word that is often used in english even today. so he is saying that in the last age of a man, the man is without eyes, taste, or anything else. he also says that this is the "last stage of all" and that it is the stage that ends a man's "history."

hope this !