叶芝于1890年3月加入玫瑰十字宗秘术组织“金色黎明修会”，并于翌年秋劝说茉德·冈入会。此处“姐妹”应即指茉德·冈。与此诗出自同一抄本，共题为“玫瑰十字”的其他五首诗《致时光十字架上的玫瑰》、《他谈论绝色美人》、《路径》、《祂，命令极地的雪原》、《梦死》也都是写给或关于茉德·冈的。

铁器时代：据西方神话传说，人类世界现在正处于堕落的铁器时代。叶芝相信历史循环说，认为上古完美的黄金时代必将在未来回归，而他本人作为智慧的化身与美的化身茉德·冈共同肩负着召唤上古爱尔兰诸神，复兴爱尔兰民族的神圣使命。

This poem and the next two come from a carefully assembled manuscript album covered in yellow cloth in black stitching and inscribed “W. B. Yeats. / ‘The Rosy Cross.’ Lyrics.” The six poems in that collection are dated variously from August to November 22, 1891. As he did with his published books, Yeats apparently meditated the sequence of poems carefully. Here is their arrangement in The Rosy Cross:

Very similar versions of the three unpublished poems reproduced in the current edition also appeared in the overlapping manuscript collection The Flame of the Spirit, a full vellum notebook that Yeats presented as a love token to Maud Gonne on October 20, 1891. In addition, a more mystic version of “To a Sister” appears in the more casually assembled white manuscript album MBY 548, which contains drafts of various Yeats poems of the early 1890s, especially those that appeared in his book The Wind Among the Reeds (1899). For more information on the three collections, and for verbatim transcriptions of pertinent parts, see Early Poetry II.

To a Sister of the Cross and the Rose: The title combines the Rosicrucian elements of Rose and Cross appropriate to the Hermetic Order of the Golden Dawn, an esoteric society that Yeats had joined in March of 1890 and that he induced Gonne to join in the autumn of 1891. Previously, they had both belonged to the Theosophical Society, whose doctrines also pervade the poem. Gonne would thus likely be the soror or “sister” addressed in the title, though Yeats characteristically avoided naming her and thus limiting the poem’s range of potential reference. Yeats variously associated Rosicrucian elements with a range of interpretations, including esoteric doctrine, erotic longing, suffering and desire of various kinds, the poetic imagination itself, and even nationalist inspiration.

Iron Times: “Iron Times” refers to the myth of a former Golden Age and its return, in contrast to current decline into an Age of Iron, as set forth for example in Virgil’s “Fourth Eclogue” and redacted in Shelley’s final chorus to Hellas, both of which Yeats drew on for “Two Songs from a Play.”