Yet abortion was not absolutely illegal in the 13 states at the time, so there was, even then, difference of opinion, among the founders, as to when life, as they were referring to it in the Declaration of Independence, begins.
Scalia is as much as saying “the people”, in the states, have no federal mandate against your interpreation and in support of abortion - as Roe tries to say. Which is why he opposes Roe - there is no Constitutional mandate in favor of abortion.
During the colonial period, the legality of abortion varied from colony to colony and reflected the attitude of the European country which controlled the specific colony. In the British colonies abortions were legal if they were performed prior to quickening. In the French colonies abortions were frequently performed despite the fact that they were considered to be illegal. In the Spanish and Portuguese colonies abortion was illegal.
According to the Oxford English Dictionary, to "quicken" means "to reach the stage of pregnancy at which the child shows signs of life."
Even Jefferson knew slavery violated the principles of the Declaration. He said so in his original draft, although that specific language was deleted in conference.
he has waged cruel war against human nature itself, violating its most sacred rights of life & liberty in the persons of a distant people who never offended him, captivating & carrying them into slavery in another hemisphere, or to incur miserable death in their transportation thither. this piratical warfare, the opprobrium of infidel powers, is the warfare of the CHRISTIAN king of Great Britain. determined to keep open a market where MEN should be bought & sold, he has prostituted his negative for suppressing every legislative attempt to prohibit or to restrain this execrable commerce: and that this assemblage of horrors might want no fact of distinguished die, he is now exciting those very people to rise in arms among us, and to purchase that liberty of which he has deprived them, by murdering the people upon whom he also obtruded them; thus paying off former crimes committed against the liberties of one people, with crimes which he urges them to commit against the lives of another.
But as Lincoln defended him writing:
All honor to Jefferson--to the man who, in the concrete pressure of a struggle for national independence by a single people, had the coolness, forecast, and capacity to introduce into a merely revolutionary document, an abstract truth, applicable to all men and all times, and so to embalm it there, that to-day, and in all coming days, it shall be a rebuke and a stumbling-block to the very harbingers of re-appearing tyranny and oppression.
Just because the principles of the Declaration have not always and everywhere been upheld doesn't demonstrate those principles were unintended or untrue.