Quarantines

[This is a letter to John Crawford on September 8, 1807:]

Thomas Jefferson presents his compliments to Mr. Crawford, and his thanks for his Observations on Quarantines, which he has read with great pleasure. Not himself a friend to quarantines, nor having confidence in their efficacy, even if they are necessary, he sees with pleasure every effort to lessen their credit. But the theory which derives all infection, and ascribes to unseen animals the effects hitherto believed to be produced by it, is as yet too new and unreceived to justify the public servants in resting thereon the public health, until time and further investigation shall have sanctioned it by a more general confidence.