“Thmei’s themes are freedom, justice, honor, divination, balance, equality, foresight and morality. Her symbols are scales or balanced items and ostrich feathers. This Egyptian Goddess of law and Mother of Virtue watches over human conduct, looking for right action, wise decisions, ethical dealings and just outcomes. On a broader scale, She also tends to matters of Universal Law, that we might learn its patterns, internalize its ideals and then use this awareness throughout the year. In some instances, Thmei is considered a prophetic Goddess to call on in determining the outcome of any course of action, especially legal ones. Egyptian art depicts Thmei bearing a single ostrich feather, the symbol of truth with self and others.
Celebrate your personal independence and break free from any constraints that seem unjust or unethical, asking Thmei for the power and courage to endure.
To make a Thmei charm that draws equity into all your dealings, find a portable token that, to you, represents balance, harmony and fairness. Put this on your bathroom scale saying,
‘Balance and harmony within this shine,
Thmei, make impartial dealings mine!’
Carry this token with you, or leave it in the area where you feel inequality or discord exists.”
(Patricia Telesco, “365 Goddess: a daily guide to the magic and inspiration of the goddess”.)
The researched information on Thmei today comes from the book entitled The Manners and Customs of the Ancient Egyptians by John Gardner & Sir Wilkinson. “This Deity had a two-fold character, as Goddess of Truth and of Justice. Her figure is frequently represented in the hands of the Kings, who present it as a fit offering to the Gods; and many, in their regal titles, are said to love, or to be loved by, Thmei. A small image of this Goddess was also worn by the chief judge while engaged in listening to the cases brought before them in court; and when the depositions of the two parties and their witnesses had been heard, he touched the successful litigant with the image, in token of the justness of his cause. A similar emblem was used by the high priest of the Jews; and it is a remarkable fact, that the word Thummim is not only translated ‘truth’, but being a plural or dual word, corresponds to the Egyptian notion of the ‘two Truths’ or the double capacity of this Goddess.
According to some, the Urim and Thummim signify ‘lights and pefection’ or ‘light and truth,’ – which last present a striking analogy to the two figures of Rê and Thmei, in the breast-plate worn by the Egyptians. And though the resemblance of the Urim and the Uraeus (or basilisk), the symbol of majesty, suggested by Lord Prudhoe, is very remarkable, I am disposed to think the ‘lights,’ Aorim or Urim, more nearly related to the Sun, which is seated in the breast-plate with the figure of Truth.
This Goddess was sometimes represented by two similar figures placed close to each other; or by one figure wearing two ostrich feathers, Her emblem; and sometimes by the two feathers alone, as in the scales of final judgement. It is to these figures that Plutarch alludes, who he speaks of the two Muses at Hermopolis, under the names of Isis and Justice. Diodorus describes the chief judge in the sculptures of the tomb of Osymandyas, with the figure of Truth suspended to this neck, with Her eyes closed; and it is worthy of remark, that the same mode of representing the Goddess occurs in the paintings at Thebes, confirming the account of the historian, and establishing Her claims to the character I have given Her.
Her principle occupations were in the lower regions, and She was on earth the cardinal virtue. For the Ancients considered, that as Truth or Justice influenced men’s conduct towards their neighbours, and tended to maintain that harmony and good will which were most essential for the welfare of society, it was of far greater importance than the the other three, – Prudence, Temperance, and Fortitude. These qualities were reflective qualities; and more immediately beneficial to the individual who possessed them, than to those with whom he was in the habit of associating.
As the dead, after the final judgement and admission into the regions of the blessed, bore Her emblem (either the ostrich feather, or the vase which indicated their good deeds, taken from the scales of Truth), and were considered approved or justified by their works, the hieroglyphics of Her name were adopted to signify ‘deceased,’ or in other words, ‘judged’ or ‘justified’.
The same idea may be traced in an expression of Plato’s Gorgias, where, in speaking of the judgements of the dead, Socrates says, ‘sometimes Rhadamanthus, beholding the soul of one who has passed through life with Truth, whether it be of private man, or any other, is filled with admiration, and dismisses that soul to the Islands of the Blessed. The same is also done by Æacus.’ Indeed, the modern Persian or Arabic expression in relation to the dead is not very dissimilar, which styles them ‘pardoned,’ or ‘to whom the mercy of God has been shown,’ answering to our more simple and matter-of-fact ‘the late,’ or ‘the departed.’
Diodorus mentions a figure of Justice without a head, standing in the lower regions, ‘at the gates of Truth,’ which I have found in the judgement scenes attached to the funeral rituals on the papyri of Thebes. In one of the subjects of a mummy case in the British Museum, the Goddess occurs under the form of a sceptre (surmounted by an ostrich feather), from which proceed Her two arms, supporting the body of the deceased. Another figure of the same Goddess, issuing from the mountain, presents him at the same time two emblems, supposed to represent water, or the drink of Heaven.
Thmei was always styled the daughter of the Sun, and sometimes ‘chief’ or ‘Directress of the Gods.’
From Her name the Greeks evidently borrowed their Themis, who was supposed to be the mother of Dikē, or Justice; but the name of the Egyptian city Thmuis does not appear to have been called from the Goddess of Truth.” 
“The Goddess Thmei, or Mei, Truth personified, is always represented as a female wearing upon Her head an ostrich-feather; because all the wing-feathers of this bird were considered of equal length, and hence meant ‘true’ or ‘correct’…Thmei is sometimes represented accompanying Thoth, and the native monarchs often presented a small figure of Truth to different deities.” 
Arundale, Francis, Joseph Bonomi, & Samuel Birch. Gallery of Antiquities, Selected from the British Museum, “Thmei“, (p. 28).
Gardner, John & Sir Wilkinson. The Manners and Customs of the Ancient Egyptians, “Thmei, Truth or Justice“, (p. 28 – 31).
Bastow, James Austin. A Biblical Dictionary, “Urim and Thummim“, (p. 755).
Encyclopaedia Britannica: A Dictionary of Arts, Science, and General Literature…, “Egypt“, (p.538).