It is not possible.to say what was the immediate cause of the passing of that part of the act which refers to manumission. It may have been the growth of a class of black freemen, or it may have been the desire to check manumission;[173] but it was probably neither of these things so much as it was the practice of masters who set free their infirm slaves when the labor of those slaves was no longer remunerative.[174] This practice together with the usual shiftlessness of most of the freedmen makes the resulting legislation intelligible enough. It provided that thereafter if any master purposed to set his negro free, he should obligate himself at the county court to secure the locality in which the negro might reside from any expense occasioned by the sickness of the negro or by his inability to support himself. If a negro received liberty by will, recognizance should be entered into by the executor immediately. Without this no negro was to be deemed free. The security was fixed at thirty pounds.[175] Whatever may have been the full purpose of this statute, there can be no question that it did check manumission to a certain extent. A standing obligation of thirty pounds, which might at any moment become an unpleasant reality, when added to the other sacrifices which freeing a slave entailed, was probably sufficient to discourage many who possessed mildly good intentions. Several times it was protested that the amount was so excessive as to check the beneficence of owners:[176] and on one occasion it was computed that the thirty pounds required did not really suffice to support such negroes as became charges, but that a different method and a smaller sum would have secured better results.[177] The burden to owners was no doubt felt very grievously during the latter half of the eighteenth century, when manumission was going on so actively, and it is known that the Assembly was asked to give relief.[178] Nevertheless nothing was done until 1780 when the abolition act swept from the statute-books all previous legislation about the negro, slave as well as free.[179]