at a word they would have circled this little bunch and driven it straight down to me ; and then it flashed into my mind that nobs had run with those collies all one summer , that he had gone down to the pasture with them after the cows every evening and done his part in driving them back to the milking-barn , and had done it intelligently ; but nobs had never done the thing alone , and it had been a year since he had done it at all .