Her tread was as light as air.

It's 1878. In February of that year, Thomas Edison had been granted the copyright of his invention, the phonograph. 

In November, the "smartly dressed" (p. 84, 2nd edition Mary Baker Eddy: The Years of Trial by Robert Peel) Mary Baker Eddy lectured at the Baptist Tabernacle in Boston, even though unprecedented difficulties assailed her. Robert Peel records that while "unhappy court cases dragged on", she "spoke with ... buoyant conviction" which attracted many newcomers. One later observer remarked that "Though she walked over thorns, her tread was as light as air" (ibid).

In her pamphlet No and Yes, she would write (p. 27: 23-26): 

"Who can say what the absolute personality of God or man is? Who living hath seen God or a perfect man? In presence of such thoughts take off thy shoes and tread lightly, for this is holy ground."

Julie Swannell