“It is more a subject of joy that we have so few of the desperate characters which compose modern regular armies. But it proves more forcibly the necessity of obliging every citizen to be a soldier; this was the case with the Greeks and Romans, and must be that of every free State.”

Referring to the importance of well trained militia amidst the populations of the states and their preferability to standing armies, in a letter to James Monroe (19 June 1813), published Thomas Jefferson to James Monroe, 19 June 1813 https://founders.archives.gov/documents/Jefferson/03-06-02-0188; though most publications of the letter since the 1830s usually provide a date of 18 June 1813, the actual manuscript seems to distinctly read "June 19 '13" http://memory.loc.gov/master/mss/mtj/mtj1/046/0800/0894.jpg; a portion of this statement is sometimes paraphrased: "Every citizen should be a soldier."
1810s
Context: !-- Dear Sir,—Your favors of the 7th and 16th are received, and --> I now return you the memoir … I am much gratified by its communication, because, as the plan appeared in the newspapers soon after the new Secretary of War came into office, we had given him the credit of it. Every line of it is replete with wisdom; and we might lament that our tardy enlistments prevented its execution, were we not to reflect that these proceeded from the happiness of our people at home. It is more a subject of joy that we have so few of the desperate characters which compose modern regular armies. But it proves more forcibly the necessity of obliging every citizen to be a soldier; this was the case with the Greeks and Romans, and must be that of every free State. Where there is no oppression there will be no pauper hirelings. We must train and classify the whole of our male citizens, and make military instruction a regular part of collegiate education. We can never be safe till this is done.