His father is explaining why the family needs money......... what they have won't last forever; Gregor had been a mainstay in helping his family financially. Obviously, this has changed.
"On the first day of his transformation, his father gave a lengthy explanation of their financial situation. Apparently they aren't so bad off. When his father's business collapsed, there was still a little money remaining, and it's been gathering interest. This news was a pleasant surprise to Gregor, who thought they had been completely ruined. He remembered the early days when he rose from the position of clerk to salesman, supporting his family with his earnings.
His father also explained that Gregor's earnings weren't all used up to support the family's living expenses, but had gone into the family's savings. Of course, this money could have gone into paying off the family's debt to Gregor's employer and Gregor could have quit sooner. But given his present circumstances, Gregor is glad his father had saved the money.
But the savings aren't enough to support the family beyond a year or two. The family needs to find employment, even though the father's obese, the mother's asthmatic, and the sister a little air-headed."
Source(s): http://www.shmoop.com/metamorphosis/part-2-summary.html