I wondered about the context of Jefferson's quote, and managed to find the entire letter. Here's a larger segment from it:
we must depend on a classified militia, which will give us the service of the class from 20 to 26, in the nature of conscripts, composing a body of about 250,000, to be specially trained. This measure, attempted at a former session, was pressed at the last, and might, I think, have been carried by a small majority. But considering that great innovations should not be forced on a slender majority, and seeing that the general opinion is sensibly rallying to it, it was thought better to let it lie over to the next session, when, I trust, it will be passed.The context was military conscription, something that had never been done before, and the larger quotation suggests that Jefferson was being strategic, figuring that a larger majority would support the measure in the next session. I don't know whether or how this context affects the use of the quote with respect to health care reform, but at least two differences are apparent: Congress has enacted similar entitlement programs in the past and there was no likelihood of a larger majority in favor of health care reform in the next session of Congress.