why does the family seem so sad?

From the text:

Poverty

‘A considerable period elapsed before I discovered one of the causes of the uneasiness of this amiable family: it was poverty, and they suffered that evil in a very distressing degree. Their nourishment consisted entirely of the vegetables

of their garden and the milk of one cow, which gave very little during the winter, when its masters could scarcely procure food to support it. They often, I believe, suffered the pangs of hunger very poignantly, especially the two younger cottagers, for several times they placed food before the old man when they reserved none for themselves.'

Too much work, too little time.

‘I discovered also another means through which I was enabled to assist their labours. I found that the youth spent a great part of each day in collecting wood for the family fire, and during the night I often took his tools, the use of which I quickly discovered, and brought home firing sufficient for the consumption of several days.

‘I remember, the first time that I did this, the young woman, when she opened the door in the morning, appeared greatly astonished on seeing a great pile of wood on the outside. She uttered some words in a loud voice, and the youth joined her, who also expressed surprise. I observed, with pleasure, that he did not go to the forest that day, but spent it in repairing the cottage and cultivating the garden.'