For some supplemens or introductions, there is “
Aquinas’s Shorter Summa: Saint Thomas’s Own Concise Version of His Summa Theologica”. There is also Summa of the Summa by Peter Kreeft. And there is A First Glance at St. Thomas Aquinas: A Handbook for Peeping Thomists (Paperback)
by
Ralph M. McInerny
** **However, there has been some modern criticism of St. Thomas:
For example,
newadvent.org/summa/301103.htm
Heretics “ deserve not only to be separated from the Church by excommunication, but also to be severed from the world by death.”
And
“On the part of the Church, however, there is mercy which looks to the conversion of the wanderer, wherefore she condemns not at once, but “after the first and second admonition,” as the
Apostle directs: after that, if he is yet stubborn, the Church no longer hoping for his conversion, looks to the salvation of others, by excommunicating him and separating him from the Church, and furthermore delivers him to the secular tribunal to be exterminated thereby from the world by death.”
Generally, I don’t think that most Catholics today would favor the extermination of Protestants by death.
Also
newadvent.org/summa/109201.htm
he held that “So by such a kind of subjection woman is naturally subject to man, because in man the discretion of reason predominates.”
Also he held that a master may strike his slave:
newadvent.org/summa/306502.htm
“And since the child is subject to the power of the parent, and the slave to the power of his master, a parent can lawfully strike his child, and a master his slave that instruction may be enforced by correction.