Arthur E. Waite - The Pictorial Key to the Tarot :
A woman, over whose head there broods the same symbol of life which we have seen in the card of the Magician, is closing the jaws of a lion. The only point in which this design differs from the conventional presentations is that her beneficent fortitude has already subdued the lion, which is being led by a chain of flowers. For reasons which satisfy myself, this card has been interchanged with that of justice, which is usually numbered eight. As the variation carries nothing with it which will signify to the reader, there is no cause for explanation.
Fortitude, in one of its most exalted aspects, is connected with the Divine Mystery of Union; the virtue, of course, operates in all planes, and hence draws on all in its symbolism. It connects also with innocentia inviolata, and with the strength which resides in contemplation.
These higher meanings are, however, matters of inference, and I do not suggest that they are transparent on the surface of the card. They are intimated in a concealed manner by the chain of flowers, which signifies, among many other things, the sweet yoke and the light burden of Divine Law, when it has been taken into the heart of hearts.
The card has nothing to do with self-confidence in the ordinary sense, though this has been suggested - but it concerns the confidence of those whose strength is God, who have found their refuge in Him.
There is one aspect in which the lion signifies the passions, and she who is called Strength is the higher nature in its liberation. It has walked upon the asp and the basilisk and has trodden down the lion and the dragon.
P. D. Ouspensky – The Symbolism Of The Таrot :
In the midst of a green plain, surrounded by blue hills, I saw a woman with a lion. Girdled with wreaths of roses, a symbol of infinity over her head, the woman calmly and confidently covered the lion's mouth and the lion obediently licked her hand.
"This is a picture of power", said the voice. "It has different meanings. First it shows the power of love. Love alone can conquer wrath. Hatred feeds hatred. Remember what Zarathustra said: "Let man be freed from vengeance; this is a bridge for me which leads to higher hope and a rainbow in heaven after long storms".
"Then it shows power of unity. These wreaths of roses suggest a magic chain. Unity of desires, unity of aspirations creates such power that every wild, uncontrolled, unconscious force is subdued. Even two desires, if united, are able to conquer almost the whole world.
"The picture also shows the power of infinity, that sphere of mysteries. For a consciousness that perceives the symbol of infinity above it, knows no obstacles and cannot be withstood".