Pirkei Avot §avot_05_15: There are four types among those who sit before the sages: a sponge, a funnel...

There are four types among those who sit before the sages: a sponge, a funnel, a strainer and a sieve.A sponge, soaks up everything; A funnel, takes in at one end and lets out at the other; A strainer, which lets out the wine and retains the lees; A sieve, which lets out the coarse meal and retains the choice flour.